Thank you, Edwina, for blowing open the hypocrisy of the Major years

If the revelations by Edwina Currie about a four-year affair with John Major had come to light any time before 26 November 1990 – the date of the second ballot for the Tory leadership following the resignation of Margaret Thatcher – he would never have become prime minister. Michael Heseltine would definitely have secured the succession and the course of history would have been completely different.

It is impossible to underestimate the seismic nature of these revelations. The first I knew of them was, like everyone else, when they were laid bare by Mrs Currie in The Times interview previewing the publication of her diaries. Never, ever, during my time in Parliament, which spanned exactly the same 18 years that Mr Major was an MP, did I hear or sniff the rumour.

This has to have been the best-kept secret of all the affairs and scandals that have hit Westminster. Of itself, if the liaison had become common knowledge in its early stages, it would have caused only a mild stir. A male and female MP having a heterosexual affair (one a junior whip, the other a vivacious, controversial backbencher) would have caused a possible resignation from the government and some mild tut-tutting in their respective constituencies. Of course, neither Mrs Currie nor Mr Major would have progressed any further. Neither would have been made a minister, let alone sat in the Cabinet or become prime minister.

So if Mr Major or his allies feel anger at being betrayed, they should perhaps reflect and be thankful that Mrs Currie kept quiet until now. If matters had burst into the headlines when Mrs Thatcher appointed Mr Major to the Cabinet after the 1987 general election victory, the stakes would have been much higher and he would undoubtedly have been forced to resign – as, of course, would Mrs Currie, who was a junior minister for two years of the liaison.

Mr Major must have been holding his breath throughout the Tory leadership battle against Michael Heseltine and Douglas Hurd. Thinking back to the profile of the Conservative parliamentary party – which in those days was the sole group to elect the leader – it is impossible to imagine them voting for an adulterer. When one remembers the fuss in 1983 surrounding the Cecil Parkinson and Sarah Keays affair (which resulted, through Tory backbench pressure, in Mr Parkinson's resignation), it seems highly unlikely that much would have changed to enable Mr Major to be treated any differently. I am utterly convinced that those who voted for Mr Major to succeed as prime minister were attracted to his "nice" and "decent" image and would have taken a very different attitude if he had been found out.

These revelations may be perceived by Mrs Currie's enemies as the vengeance of a scorned woman. I am grateful that she has made them. As a government whip in Mr Major's administration, I was expected to fall on my sword after a tabloid newspaper revealed that I had been on holiday with an underage gay man. It was felt that scandals such as mine and those involving David Mellor, Tim Yeo and the whole supporting cast of other ministers and MPs caught on the wrong side of the "Back to Basics" campaign were undermining the integrity of the government. Those MPs and ministers are now entitled to feel more than a little peeved and bitter. In fact, they should, like me, be downright bloody angry at the hypocrisy that was at the heart of the Major government.

Of course, I feel sorry for Norma Major that Mrs Currie has dragged up all these events from the past. But it seems incredible to expect such a fantastic secret to go with her to her grave. I am amazed that Mr Major ever thought something like this could be kept secret. I do not seek to be judgemental – heaven knows I am in no position to moralise. But it seems to me that there is no difference between his transgressions and the rest of us, except that we got found out and he did not.

These revelations, coming in the week that another of Mr Major's creations, Lord Archer, has been hitting the headlines, continue to cast a long shadow over the Conservative Party.