How would they rate Leicester and Northampton? The other 3 are a fair bit behind those 2. My opinion would be that those 2 sides are good enough for Conference South but not NCL. Coventry and Nottingham would be sort of top end or midtable division 2 IMO as they're comparable to Dewsbury Celtic. Much too good for a midlands premier and easily capable of the national travel as up north and down south is equidistant roughly.
The problem is the London clubs may whinge about having to play us but we don't have a local option. Bristol have a similar problem in that regard but might struggle on the field in the NCL. They'd be too good for midlands premier though.
Said it's a good standard a lot slower than the Yorkshire league and not as aggressive, also said they are a great bunch of lads.