Sounds like this one - the PM is a patient in it. Haven't watched it in years...
Foreign Body (1986)
Smudge
I'm asking this on behalf of my mother, who saw this comedy on Channel 4 at Easter a year or two ago, so sorry if the details aren't the most comprehensive! She thinks it must date from the 1960s or 1970s. Plot is, a fraudster from the Indian subcontinent ends up impersonating a doctor on Harley Street, treating people for back complaints. At one point, the Prime Minister is one of his patients. There's slapstick involved, such as the couch going up and down wildly while a patient is lying on it.
Any ideas?
Sounds like this one - the PM is a patient in it. Haven't watched it in years...
Foreign Body (1986)
Smudge
That's the one, just showed my mother a trailer I found of it! Cheers