It is possible. Plum moths do lay a lot of eggs. Next year buy and hang the Plum moth traps in your tree. They are easily purchased from most Garden Centres.

Thankyou Owdboggy,This tree is in its fourth year and has never given trouble before.I shall do as you suggest.
All the green plums ( loads of them ! ) will be falling beneath the tree,do the maggots hang around to influence next year ? would the maggots still live if I dump them in the compost ?Can you tell me what happens to them next ?

Collect up the fallen fruit and destroy rather than compost. The worms will hatch into moths which fly off and overwinter elsewhere to return and lay their eggs to continue the cycle.
There is another simlar pest called Plum sawfly which do the same sort of thing, but they attack the fruit early on in the year, Victoria is a favourite of theirs. These are much harder to deal with, but are much rarer than the Plum moth.

Thank you Owdboggy.Can you also tell me if those eggs were laid into the flower ? they seem to be in every plum and no sign of how they got in there !The maggots are very tiny and seem to be close to the stone .My son ate a couple before we spotted the black goo ( ha ha )

The female makes a tiny hole in the plum to lay her eggs. The only sign is sometimes, in a good damp season, the plum leaks juice, but generally there is no easily seen external sign.

82 aand still learning ! thankyou for your patience Owdboggy

Pleasure.