Harry Grout (nicknamed "Grouty") was an antagonistic character in the British sitcom Porridge. Despite appearing in only three episodes (and referred to in many more) and the film, he is one of the best-remembered characters from the series, and has the role of the main villain of the series, surpassing even Mackay.
He was played by the late Peter Vaughan.
Slade Prison is officially run by the Governor, but the prisoners know better. Grouty is the real muscle behind what goes on in the prison. Even the guards fear him, as evidenced by him having his own cell which is lavishly decorated, filled with valuable prison commodities and he is surrounded by his own 'heavies'. Grouty's offical job in the prison is to look after the swimming pool, which is particularly easy as the prison does not have a swimming pool. Something Grouty marks down to being clerical error, but is really his way of getting out of having to work.
Grouty is feared by all the prisoners, even Fletcher is terrified of him and near panics whenever he is summoned to Grouty's cell. His schemes include running a drugs ring, funded by the doctor's office and rigging boxing matches. If crossed, Grouty has little hesitation in setting one of his various heavies on those who displease him.
Grouty also arranges things such as prison breaks, as seen in the Christmas special "No Way Out," in which the major plot involves his trying to arrange a breakout plan, with much help from an unwilling Fletcher. Eventually, Fletcher reveals the tunnel that was dug to Mr. Mackay but ends up landing himself in the prison infirmary. He also successfuly causes the break out of another big time criminal (in the film).
Although prefering to appear friendly (hence his nickname Genial Harry Grout) Grouty's a monster, when crossed or even just annoyed, he has no problems setting his army of goons on whoever is responsible, nor having any trouble having them torture other prisoners for things, the fact he gets away with performing these acts in broad day light, is proof of his power in the prison.
Interestingly, Grouty never appears in the same scene as Mr. Mackay, and accordingly viewers are never certain whether Mackay has ever attempted to tackle Grouty's control of the prison.