What is this thing?

a car

A Hillman Minx. Take your pic from here - http://en.wikipedia.org/wiki/Hillman_Minx - as to which model it is but I think an early 1950s Mk V or VI.

This Hillman Minx could be even older , phase 3 or 4

I was thinking '52 Fiat.

The reason I said it might be Mk V or VI is that according to the wiki article that was the only model sold in the US and I thought the pic looked to have been shot there.

This 49 Hillman Minx has the same low tail lights.

That is either a phase III 1185 cc 35 hp, or phase IV 1265 cc 37.5 hp, 1948-49 vintage, both flathead fours. They were a popular car here {North Vancouver, BC} in the early 50's. In my high school years in the 60's there were several minx convertibles of that vintage in the school parking lot. They were cheap to buy, cheap to run and parts were plentiful. They couldn't get out of the way of their own shadow, but that didn't seem to bother the girls they attracted too much when the tops were down - and the boys were happy!!!

Terry