Help remembering early 80s UK political drama

[Kiltie]

I remember watching a UK produced drama series on UK TV around the early 80s.

As I recall, it was about an MP who made it to PM and he was straight as a die.

Never told lies or put spin on anything he said and this unsettled those opposing him.

I seem to remember he lived with his mother.

I can picture the lead actor (stout, slicked back black hair, English) but can't remember the name.

Any ideas?

[Kiltie]

That's it, thanks very much.

Late 80s and not early 80s as I thought.

It was the Corbyn phenomenon that remined me of it.

Thanks again.