Ministerial bag-carrying eats into their social and family lives while high standards of personal behaviour are expected.
The quid pro quo is a possible move up the greasy pole to a junior ministerial position. Mr Riddick, MP for Colne Valley, West Yorkshire, since 1987, was on the promotion list for next week's reshuffle. The pole is likely to have proved too greasy this time.
He once sought to challenge the myth that the popular press was overwhelmingly right-wing and hostile to the Labour Party, and was often given to complaints of 'biased' television programmes. But he had singled out Rupert Murdoch for special praise. Perhaps he will now revise his views.
An eager right-winger, Mr Riddick, 38, has strong views on a number of issues. His detestation of the closed shop encouraged him to join the ultra-right Freedom Association in 1976.
More recently, he has waxed long and hard about corruption at Labour-controlled Monklands District Council. While a product of Stowe whose grandfather was an MP and whose father owned a mill, the former Coca-Cola sales manager sports the jaunty grin of a second-hand car salesman. He is sometimes described as a lookalike from the Adams family.
Notwithstanding, or perhaps in spite of, his attendance at Warwick University, Mr Riddick has little truck with trendy ideas. He does, however, comply with Commons rules and reveals his Lloyd's syndicate numbers in the Register of Members' Interests.
The same cannot be said for the wealthy Mr Tredinnick, one of 11 Tories recently reprimanded by the Select Committee on Members' Interests for failing to do so. Both men are Lloyd's losers, with Mr Tredinnick's losses reputed to be particularly heavy.
Eton-educated and a former Grenadier Guardsman, Mr Tredinnick, 44, is a good deal 'wetter' than Mr Riddick - although that would not be difficult. A top- drawer education and generations of inherited family money from Cornish tin mining seem to have produced a stiff-necked Commons performer. But his Commons contributions can be constructive.
He also demonstrated a gentlemanly willingness to share some of his financial fortune by voting against the abolition of higher rates of income tax and capital tax under Margaret Thatcher. Mr Riddick tends towards the crude knocking question.