Dad swears they are 27", going off what he read on the tyre side walls...
Tricky, as he is miles away and not good with tech! Knowing where he got it from, I am convinced this is a bike I used to work on when I was in the cycle trade... Every year we had it in for a service.
It's a 1990 King of Mercia in touring geometry.
I too would be inclined to say the wheels would be 700 as I have an eighties King of Mercia tourer and a nineties King Of Mercia road and both are 700c.
But you never know as you could order what you wanted.
Cheers