Many thanks for your warm welcome.
I seem to recall a post by Peter J which described a similar situation (less the heated seat) of the cockpit becoming very warm and the engine heat overwhelming the a/c - his solution from memory was to close the vents and turn off the a/c which is advice we have taken on board and it seems to work okay unless stuck in slow moving traffic. This is my first Morgan and so I'm wondering if anyone has managed to upgrade their a/c or come up with any other solution for cooling the cockpit?