As you noted, he used Eric Blair in his family life even though he once wrote
It took me nearly thirty years to work off the effects of being called
cited in Jeffrey Meyers, Orwell: Life and Art (2010)
and this private use is most graphically illustrated by his gravestone:
Attrib: Brian Robert Marshall [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
However, he also went by his birth name in other areas of his private life. Most obviously, this included people he knew before he adopted George Orwell as his pen name with the publication of Down and Out in Paris and London in January 1933, but it's more complicated than this. This Newsweek review of Bernard Crick's book George Orwell: A Life notes
His simultaneous use of two names during most of his adult life was
one method of cultivating the Mystery around him; another was his
habit of keeping different groups of friends very much apart. Crick
says even years after Orwell's death people were often astonished to
discover who else he knew.
At the same time, Crick
rejects the notion that Eric Blair (his real name) transformed himself
into someone different called "George Orwell"
John Rodden, in George Orwell: The Politics of Literary Reputation, also notes this tendency of Orwell / Blair to compartmentalize his life. This article elaborates further on this:
Over the years George Orwell would have his own life, seperate from
Eric Blair. Orwell had his own set of friends, and Blair HIS own. It
was part of Orwell’s love of putting his life into compartments.
Friends would talk about how Orwell would keep friends they had never
met, as if Orwell made an effort to keep everybody from knowing
Thus, how he was addressed at 'gatherings' would have depended on which set of acquaintances he was with.
When Orwell / Blair, after the death of his first wife, went to live on the Scottish island of Jura, the "locals knew him by his real name of Eric Blair". He also used his real name for legal purposes: for example,
Burmese Days, written by “George Orwell,” was copyright under his real
name, Eric Blair.
Source: J. Meyers