He was the half-brother of the Empress Matilda, and her chief military supporter during the civil war known as the Anarchy, in which she vied with Stephen of Blois for the throne of England.

[13]: 200  Bristol Castle was Robert's principal seat in England and he constructed additions to its exterior fortifications and rebuilt the interior.

When he was advised, as the story went, to claim the throne on his father's death, deterred by sounder advice he by no means assented, saying it was fairer to yield it to his sister's son (the future Henry II of England), than presumptuously to arrogate it to himself.This suggestion cannot have led to any idea that he and Stephen were rivals for the Crown, as Geoffrey of Monmouth in 1136 referred to Robert as one of the 'pillars' of the new King's rule.

With the success of Stephen in England, Robert and Matilda returned to Normandy, where the earl recruited fresh levies.

However, it came to a quiet close in 1147 when Robert died and the queen and her son, now deprived of Gloucester's protection, returned to Normandy.

His efforts to gain the crown for his sister by capturing King Stephen and her own actions in London are part of the plot in The Pilgrim of Hate.

Robert's travels to persuade his brother-in-law to aid Empress Maud militarily in England is in the background of the novel The Rose Rent.

His return to England when Empress Maud is trapped in Oxford Castle figures in The Hermit of Eyton Forest.

Robert's success in the Battle of Wilton leads to the death of a fictional character, part of the plot of The Potter's Field.

In that last novel, Brother Cadfael speculates on the possibly different path for England if the first son of old King Henry, the illegitimate Robert of Gloucester, had been recognised and accepted.

He was also central in the struggle during the Anarchy as portrayed in Ken Follett's 1989 novel The Pillars of the Earth, in the 2010 mini-series, and in the 2017 video game of the same name too.