Thank you for all the replies folks - much appreciated. Having lived with my M3W for 5 years I am very well aquainted with my local Morgan dealer (Bell & Colvill in Horsley) and they're only 6 miles up the way, which is handy.
Good to hear that the cars can be fettled to be broadly water tight and I'd not thought about the obvious usefulness of the hood stowage area when the roof is up - neat.
I think I'd already read about the need for a sump guard and I didn't try to see if there was any audio kit fitted. There appeared to be what looked like speakers in the front of the doors, but no obvious head unit. I guess it's not difficult to get some sounds in there, even just a basic radio that does Bluetooth streaming?
Next job will be to get Mrs R1NGA down to see one and then assess WAF thereafter. Right now it's struggling to get much of a +ve reading at all from pictures however....!