I’ve heard people say Cross Fell is the longest. It certainly is long.
I think Great Dunn Fell is the longest road climb – comes in at just over 600m vertical if I remember. Next to Cross fell, you can ride up the road and down the bridleway.
Unless the sign at the bottom of Cragg Vale and all the blurb on the internet is wrong, Cragg Vale is the longest (not highest) continuous road ascent/descent in England.
Grum technical I suppose that as a road climb Cragg vale is the longest as the one to the top of Cross Fell is a Bridleway which has been tarmacked to allow access to the air traffic control stuff on the top.
Cross Fell is probably the only Cat 1 climb in the UK.
The road to the radar station on Great Dun Fell [edit – not Cross Fell Dales rider] is the biggest vertical drop on tarmac IIRC, it’s not a public road but is a bridleway, and there are longer descents with less vertical drop. A good climb, but Cat1? I dunno about that.