Nothing to be concerned about. New leaves are often last to drop and the behaviour of the plum isn’t relevant. They often drop before apples and pears. Also you don't say where you’re located. Round here there are still quite a lot of leaves still to fall. The pear will do its thing when it’s ready.

Thanks for the timely response, the funny thing now being is I went out shortly after writing this and there looks to be some bronzing on the smaller leaves, it won't take very long for the rest to follow. 🤭

Hopefully some nice big healthy pears to compensate me next year now.

location... big city name ...

one reason that something might not drop leaves in fall .. is too much fert.. to late in the season .,.. the tree forced into aggressive late growth.. instead of slowing down for dormancy .... is this possible ... if this happened.. you might also have branch die back in spring.. depending on how cold you get in your location ....

other than that ... you cant really compare apples to oranges.. or in this case pear to plum ... each tree will do what it darn well pleases.. in its own time ... like children ... they are all different.. even if the same type of tree ... micro climates can also affect such ....

i wouldnt worry about it ... short of going out there and clipping them off.. whats to be done???

ken