Should politicians have a sell-by date?

I was listening to Radio 4 a few weeks back (I think it might have been Front Row) and heard Harriet Harman being interviewed about her new role as shadow for the Culture, Media and Sport brief.

Dearie, dearie me.

She was given ample opportunity to show her more human side. Indeed the brief surely requires that the holder is able to show how they have enjoyed culture and hence inject a bit more of the personal? No chance from Harman. She came across like an "I speak your policy" robot. The only thing I can really recall her saying was about how vital the performing arts and film etc. are to the economy. When something like this is reduced to such technocratic terms it makes me want to weep.

But the more I have reflected on it, the more I am thinking that this sort of thing is inevitable. Harman has been an MP since 1982 when she was 32 years old. She is now 61 so that is almost half of her life and the vast majority of her adult life. In other words cutting edge television when she entered parliament was Game For A Laugh.

I know the pressure that is on MPs and the hours that they have to work so to expect an MP of nearly 30 years standing, with the last decade near the top of government, to be in touch with popular culture is unrealistic.

It further occurs to me that maybe this is part of the problem. I imagine if Chuka Umunna or Rachel Reeves for example had had that role they would have come across in a much more human way. Because they have lived a relatively normal life until recently where they would have had the time and inclination to keep in touch with popular culture.

So should there be a shelf-life for politicians? Should we say after maybe 20 or 25 years, thanks very much for your service but you cannot serve any longer than that an an MP (or in a reformed upper chamber)?