[RsT]

Our pumpkin plant (which went in very late and sad from the local garden centre for 10p!) now has three pumpkins albeit not very big.
I want to grow them as long as possible but do the pumpkins need to be harvested before a frost?
Don't want to risk losing them particularly as the biggest is promised to our son for Halloween! Another ploy to keep him interested in the veg garden.

[JayG]

Yes, frost will kill both the plant and damage the fruits, but before that you will find the plant starts to weaken as the cooler temperatures and shorter days take their toll.

Keep them going as long as possible until it is pretty clear the plants are about to give up the ghost!