As a club member a good starting point would be to look at the ads in the club magazine...
You need to ring round the main classic Land Rover/car insurers. There are several to choose from.
In no particular order:-
Peter Best
Footman James
Adrian Flux
Good companies will know all about Series Land Rovers, SWB, LWB and all the model variations.
Don't deal with anyone who starts asking questions which suggest they don't know about Land Rovers.
Insurance is a personal thing, depending on you, your age, experience, driving record, where you live and your occupation.
Also depends on what cover you want. Most now offer free breakdown/accident recovery - some even for Europe. Then there's limited mileage, and agreed vehicle value.
What's a good company, a good deal for one may not be for someone else.
The real test comes when you have an accident, or a total loss - fire/theft etc.
How quickly they pay up, and a fair amount
I'm with RH (2 vehicles) but never had to claim.