I am not an expert on the British peerage, but I know of some evidence to suggest that possibly some hereditary British peers moght have lived a lifestyle that might be considered by some to be low enough to be considered lower class.
Long Answer in seven parts:
Evudence for the possibility of hereditary British Peers living lower class lifestyles.
Part One: Some possible and disputed royal analogs of British peers living lower class lifestyles.
There was a period in Norwegian history when a few men came to Norway and claimed that they were illegitimate sons of Norwegian kings who had been born of affairs those kings had in foregin lands. Some of those claims were accepted and some of those claimants became kings or co-kings of part or all of Norway.
So there is considerable speculation and debate about which of those claims were true and which were not.
King alexander III of Scotland and his wife Margaret had a son Alexander and a daughter Margaret. The daughter Margaret married KIng Eric II of Norway and had a daughter Margaret born in 1283. King Alexander III's daughter Queen margaret of Norway died and then Prince Alexander died childless, leaving KIng Alexander III without any heirs except for his Norwegian granddaughter Margaret. So King Alexander III remarried and had the nobles in Scotland vow to make his grandaughter Margaret the heir if he died without any children by his second marriage. Then Alexander III died in a riding accident in 1286 and his widow did not have a posthumous child, so Margaret the Maid of Norway was recognized as the rightful Queen regnant of Scotland. Margaret the Maid of Norway sailed to Scotland in 1290 aged 7 but died in the Orkney Islands.
In 1300 a woman and her husband sailed from Germany to Norway, where she claimed to be Margaret the Maid of Norway, who had been kidnapped when she was said to have died. The woman was eventually burned at the stake. And she was almost certainly an impostor. But if she or any of the men claming to have been illegitimate sons of Norwegian kings were telling the truth, they might have lived in poverty and a lower class life style, depending on the wealth of those who raised them, before coming to Norway.
Kaspar Hauser (1812? – 17 December 1833) was a German youth who claimed to have grown up in the total isolation of a darkened cell. Hauser's claims, and his subsequent death by stabbing, sparked much debate and controversy. Theories propounded at the time identified him as the grand ducal House of Baden, hidden away because of royal intrigue. These opinions may or may not have been documented by later investigations.1 Other theories proposed that Hauser had been a fraud.
Kaspar Hauser was probably not the rightful Grand Duke of Baden, but if he was he would have lived a lifestyle much lower than royalty before he appeared in Nuremburg in 1828.
So with those examples, one can agree that it is theoretically possible for the rightful possessor of a British peerage to live a much lower class lifestyle than that of a peer.
Part Two: James Annesley, possibly the rightful Earl of Anglessey.
James Annesley (1715 – 5 January 1760) was an Irishman with a claim to the title Earl of Anglesey, one of the wealthiest estates in Ireland. The dispute between Annesley and his uncle Richard Annesley was infamous in its time, but his story is perhaps best known today as a possible inspiration for the 19th-century novel Kidnapped by Robert Louis Stevenson and other works.
James Annesley was allegedly disowned by his father and tossed out into the streets, and then kidnapped age about 12 by order of his uncle Richard Annesley and sold as an indentured servant in Delaware, while Richard claimed the Earldom and the estates as the heir. So if James Annesley's story was true, he was living in poverty and then working as an indentured servant while being the rightful Earl of Anglesey.
Part Three: James Fitzgerald, rightful 12th Earl of Ddesmond.
Thomas Fitzgerald, 11th Earl of Desmond in Ireland (1454-1534), married as his second wife Kathleen Fitzgerald, "the Old Countess of Desmond", who survived him by about 70 years and so was reputed to have lived to be 120 or even much older.
His heir was his grandson, James Fitzgerald, who came from the court of King Henry VIII with his supporters to claim the Earldom. But his grand uncle Sir John Fitzgerald claimed the earldom and succeeded in possessing it de facto . When John died in 1536 his son James Fitzgerald became the de facto Earl of Desmond. James Fitzgerald the rightful, de jure, Earl of Desmond was murdered in 1540 without children. And it is possible that James Fitzgerald the de jure Earl of Desmond was not rich enough to live the lifestyle of an Irish Earl.
And no doubt there are other examples of disputed successions to various noble titles, and possible examples of the rightful peer not being acknowledged as such.
Part Four: Inheritance of titles by distant cousins who might not be rich enough for a peer's lifestyle.
I note that some British peerages can pass to heirs general, meaning a women a can inherit if her father has no sons. Most British peerages pass to heirs male ,by agnatic (male line only) succesion, so if a peer dies with only daughters, the peerage will not go to his oldest daughter, but to his closest relative descended in male line from the man originally grnted that peerage.
And it is very common for peerages that go to heirs male, and specifically go to "heirs male of the body", that is to the agnatic heirs descended from the original grantee of the peerage and not to persons descended from his brothers or other relativws.
Suppose someone was granted a peerage in 1521, 500 years ago. If his family has an average of three to four generations per century, the present day peer could be in the fiftheenth to the twentieth generation from the original grantee. Suppose that peer dies in 2021 without any children, or without any male children. His daughters, if any, would not be eligible to inherit the peerage. So the peerabe would pass to his nearst agnatic relative descended from the original grantee. That could be his brother, uncle, nephew, 1st cousin, 2nd cousin, 3rd cousin, 4th cousin, etc. It would be unusual, but possible, for the nearest agnatic descendant of the original grantee to be descended from a younger son of the original grantee and thus be a 13th to 18th cousin of the peer who dies in 2021. Such a distant heir could obviously not be as rich as the peer and might have a lower class lifestyle before inheriting the title. And maybe he still has a lower class lifestyle after inheriting the title if the peer leaves his wealth to a daughter or someone else who is more closely related to him but unable to inherit the peerage.
A similar situation is in a novel called the The Dukes by Malcolm Ross. In 1849, the childless 5th Duke of St. Omer hires investigators to find if he has any relatives elible to inherit the Dukedom. The closest heir they can find is a struggling entrepreneur named Alfred Boyce who is one step away from his creditors, and clearly has not previously lived the life style of a British peer. One plot involves another family, living in Australia, who have rival claim to the Dukedom, and it turns out that they are the rightful heirs but never prove their claim. Thus in that novel the rightful de jure Duke never gets to live like a duke.
Renaud de Courteney (died 1190), a French noble, moved to England. His descendant Hugh de Courteney, a great grandson of a women of the Redvers family who were Earls of Devon until 1262, was made Earl of Devon in 1335. It is uncertain whether this was a new earldom or a continuation of the earldom of the De Redvers earls. The earls of Devon were involved with the royal court and their title was confiscated and restored several times duirng the Wars of the Roses and the Tudor dynasty.
In 1553 Edward Courteney was released from prison by Queen Mary and a new earldom of Devon was created for him. He died childess in Italy in 1556, and it was believed that the earldom created for him died with him.
Almost 280 years later, William Courteney (1777-1859) was an MP form 1816-1828, and Clerk Assistant to Parliament when he discovered that the patent for the grant of the Earldom of Devon to Edward Courteny in 1553 "differed from earlier patents in that it granted the earldom to his heirs male forever, rather than to the heirs male of his body." Thus the childless William Courteney (c. 1768-1835), 3rd. Viscount Courteney of Powderham, was de jure the 9th Earl of Devon.
So in 1831 the 3rd Viscount Courteney officially became the Earl of Devon, and when he died childless in 1835, his 3rd cousin & closest agnatic relative, William Courteney (1777 - 1859), became the next Earl of Devon, and also became much richer when he inherited many estates from the 9th earl.
The two William Courteneys, the 9th and 10th earls of Devon, were 3rd cousins and so had a common great great grandfather. They were agnatic descandants of Sir Philip Courteney (1340-1406), a younger son of the 2nd/10th earl Hugh de Courteney (1303-1377).
Edward Courteney (1527-1556) who they became the heirs of, was descended in 7 generations from the 2nd/10th earl Hugh de Courteney (1303-1377) The 9th and 10th earls were descended in 16 generatons, if I counted corrrectly, from the 2nd/10th earl Hugh de Courteney (1303-1377), thus making them 5th cousins 9 times removed of Edward Courteney (1527-1556) who they inherited the earldom from.
And it is possible that in some cases a distant cousin who is rather poor could inherit a peerage without inheriting any wealth and remain poor.
Part Five: A Fugitive peer.
Richard John Bingham, 7th Earl of Lucan (b. 1934), had an unhappy marraige. His children's nanny, Sandra Rivett, was murdered 7 November 1974, and the earl's wife was also attacked - she said the earl was the attacker. The earl disappeared.
There have been hundreds of sightings of the 7th Earl over the decades, but none proved. He was declared presumed dead in 1992, declared legally dead in 1999, and a death certificate was issuded in 2016 when he would be 82 if still alive, and his son was recognized as the 8th Earl of Lucan.
Since nobody knows what happened to the 7th Earl, and since he was a wanted fugitive, he may have lived for a time in the criminal underground of some location, having a lifestyle very different from that of most peers.
Part Six: A heir who doesn't know.
I read a book by John Ian Robert Russell (1917-2002), where he stated that his parents, who were socialists, didn't tell him anything about his father's parents until he was 16 and they took him to visit them - at Woburn Abbey, the home of the Dukes of Bedford. He eventually became the 13th Duke of Bedford.
And if the 12th Duke had moved his family to a foreign counntry and he and his wife died in an accident without leaving a forwarding address or telling his son about his ancestry, the son might have become the rightful Duke of Bedfored witout knowing it, or living the lifestyle of a peer, for a long time.
Part Six: The Cottage Countess.
Henry Cecil (1754-1804), was a well to do landowner, but fell deeply in dept. His wife Emma had an affair with the Reverend William Sneyd and eloped with him in 1785. Henry made arrangements for his estate income to pay off his depts and left, changing his name to Jone Jones. He lived modestly in the Shropshire village of Great Bolas, and in 1790 he married Sarah Hoggins, the 16-year-old daughter of a local farmer. In 1793 Henry inherited property from his uncle, and he took them to their new home - Burghley House, the great mansion of the Earls of Exeter.
Henry's wife Sarah was nicknamed "The Cottage Countess" because of her dificulties n adjusting ot her new lifestyle. She died in 1793,and Earl Henry became Marquis of Exter in 1801.
Part Seven: Conclusion.
Going by those examples, it seems possible to me that some peers have lived a lifestyle which could be considered lower class. It is even possible that some of the examples I gave might be considered sufficienlty lower class lifestyles.