Depends on the age of your Morgan if the majority of fasteners on the car (body, chassis, engine etc) are Metric or Imperial. I love Snap On and that's all I bought when I did this for a living, then when I was not using them every day I went on to companies like Blue Point and Facom. I have been asked more than once to put a kit together for someone (apprentices through to keen enthusiasts) and it's all about how often you will use? The more you use them the easier to specify higher quality. Once your through that minefield it's a case of drive size, hard to justify a full set at 1/2" drive these days as 3/8" drive are much stronger and easier to use and get into tight spaces. Finally there are schools of thought on socket types, Hex, Bi-Hex, Flank Drive????? And you thought this was easy ;-).
If it were me and it was for a keen hobbyist I would look to a decent mid range 3/8" drive socket set with a nice 1/4" drive small set for all the intricate work, have a look at the Halfords professional range and a good clue is to pick up the ratchet, click on a short extension....how fine is the ratchet teeth? (You want to move the ratchet through as small an angle as possible to go to next tooth so fine teeth are an advantage) second, holding the short extension how much play (waggle) is there in the ratchet mechanism, as little as possible is good.
Hope that helps and happy shopping
