The punishment of being "Hanged, drawn, and quartered" (sensu stricto, it should always be 'hanged', rather than 'hung') was abolished in England by the Forfeiture Act 1870:
From and after the passing of this Act such portions of the Acts of the thirtieth year of George the Third, chapter forty-eight, and the fifty-fourth year of George the Third, chapter one hundred and forty-six, as enacts that the judgement required by law to be awarded against persons adjudged guilty of high treason shall include the drawing of the person on a hurdle to the place of execution, and, after execution, the severing of the head from the body, and the dividing of the body into four quarters, shall be and are hereby repealed
In fact, being 'drawn' in this context actually had nothing to do with the disembowelling of the traitor. It referred to the fact that he was fastened to a hurdle and drawn by horses to the place of execution.
Disembowelling the traitor had been abolished by the Treason Act, 1814, which replaced it with post-mortem decapitation. The preamble to the 1814 Act describes the punishment as it had existed up until that time:
Whereas in certain cases of high treason, as the law now stands, the sentence or judgement required by law to be pronounced or awarded against persons convicted or adjudged guilty of the said crime in such cases is that they should be drawn on a hurdle to the place of execution and there be hanged by the neck, but not until they are dead, but that they should be taken down again, and that when they are yet alive their bowels should be taken out and burnt before their faces, and that afterwards their heads should be severed from their bodies, and their bodies be divided into four quarters, and their heads and quarters to be at the King’s disposal.
In relation to the Gunpowder Plot, it is worth noting that even though Fawkes had jumped from the gallows and broken his neck, his body was still quartered and beheaded, thus ensuring that the full punishment was carried out. However, I can find no reports in contemporary accounts that his body was castrated or eviscerated.
I believe that the last people to suffer the punishment in England were Edward Despard and his six co-conspirators in the Despard Plot. They were drawn, hanged and beheaded at Horsemonger Lane Gaol in modern Southwark in 1803.
However, if you are after the last person to suffer the full extremities of the punishment, that dubious honour falls to David Tyrie who was hanged, drawn quartered, and also disembowelled & castrated while still alive, in Winchester on 24 August 1782.
The Gunpowder Plot and the Eighth Amendment.
On particular fact in regard to the trial of the Gunpowder Plotters that may be of interest in the context of the prohibition against "cruel and unusual punishment" contained within the Eighth Amendment to the US Constitution is to be found in the speech by Sir Edward Coke ahead of the verdict.
Transcripts of the trial are to be found in multiple sources. A readily accessible example can be found in Volume 2 of Cobbett's Complete Collection of State Trials and Proceedings for High Treason. There are also transcripts on several websites, for example here.
In his statement, Coke makes it clear that, in his opinion the crimes of the plotters deserved special punishment, but that:
"... howsoever these Traitors have exceeded all others their Predecessors in Mischief, and so Crescente Malitia, crescere debuit & Pæna; yet neither will the King exceed the usual Punishment of Law, nor invent any new Torture or Torment for them."
The transcript goes on to describe that punishment in detail:
For first, after a Traitor hath had his just Trial, and is convicted and attainted, he shall have his Judgement to be drawn to the place of Execution from his Prison, as being not worthy any more to tread upon the Face of the Earth whereof he was made: Also for that he hath been retrograde to Nature, therefore is he drawn backward at a Horse-Tail. And whereas God hath made the Head of Man the highest and most supreme Part, as being his chief Grace and Ornament, Pronaque cum spectent Animalia cætera terram, Os homini sublime dedit; he must be drawn with his Head declining downward, and lying so near the Ground as may be, being thought unfit to take benefit of the common Air. For which Cause also he shall be strangled, being hanged up by the Neck between Heaven and Earth, as deemed unworthy of both, or either; as likewise, that the Eyes of Men may behold, and their Hearts contemn him. Then he is to be cut down alive, and to have his Privy Parts cut off and burnt before his Face, as being unworthily begotten, and unfit to leave any Generation after him. His Bowels and inlay'd Parts taken out and burnt, who inwardly had conceived and harboured in his heart such horrible Treason. After, to have his Head cut off, which had imagined the Mischief. And lastly, his Body to be quartered, and the Quarters set up in some high and eminent Place, to the View and Detestation of Men, and to become a Prey for the Fowls of the Air.
So, the punishment was undoubtedly cruel, but it was considered appropriate, and by no means unusual, by Sir Edward Coke - a man who many consider to be "the greatest jurist of the Elizabethan and Jacobean eras".