Anyone got a B47 (old style) handy?

[Nigel]

I've brought my chart table seat cushion home to make a new one, but in hindsight I should have measured the seat, and the radius of the curve in the corner.

Anyone got a B47 (mine built in 2000) they can measure this on?

For the radius, an approximation would be fine, like "fits small/medium/large can of baked beans"