One of the strange results of advancing into old age is that it becomes increasingly difficult to believe how long one has been doing things. This struck me with particular force when I was chucked out of the Conservative Party last week. Someone asked me how long I had been involved in the party - and this made me realise, with something of a jolt, that the answer was about 40 years.

Of course, by comparison with some of the other people who have been removed recently, like Nicholas Soames and Ken Clarke, this is a mere trice. But it still strikes me as an extraordinarily long stretch, and forces me uncomfortably to acknowledge my advancing years.

Being thrown out of your party when you are an MP also has the rather strange effect that you are sitting in the same place, doing the same things, surrounded by the same people and thinking much the same thoughts; but you are not, for parliamentary purposes, the same kind of being. There are various ways in which this fact begins to dawn on you. Some of them are very quaint.

For example, I was recently alerted by the parliamentary authorities to the fact that the all party parliamentary group on prescription drug dependency now faced a problem. This group, which I chair, has recently played a part in prompting Public Health England to produce a study showing that about a quarter of the adult population are now prescribed drugs to relieve pain, anxiety, depression and other such conditions, and that many people are kept on these drugs for far too long, while others are taken off them much too suddenly and with inadequate support.

In coming weeks, I hope that the all party group will be able to work with the Department of Health and the Royal Colleges to implement the very sensible recommendations made in Public Health England’s report.

But, say the parliamentary authorities, the all party group (if it is to retain that status) will now need to recruit a Conservative officer.

‘Why’, I ask myself, ‘does the group need to recruit a Conservative when it’s got me as its chair?’. And then, of course, I realise that this is exactly why it needs to recruit a Conservative - as the Chair is now an Independent.