Well I had an interesting time with this one. As Dave says above, they are underwritten by UK Insurance in Leeds, of which Green Flag is the trading name. This has now become
UKI Partnerships, from the restructured Direct Line Group.
Some others in this partnership may also be of interest and are as follows:-
Green Flag Motoring Assistance
Saga Motoring Assistance
Privelege Insurance
Tesco Motoring Insurance
Tesco Home Insurance
Vauxhall Motor Insurance
Those were the few that I could find since I picked this up last night.
The main switchboard
0113 3904000
will put you through to any of them.