Apples and pears. And plums and cherries

How old can apple trees be? Following up on my last post and the note about the PTES orchard survey project, I was at the NGS open day at Kidbrooke yesterday. While I was there I looked at the walled garden and its fruit trees in a bit more detail and then compared them with the planting plan from about 1810 (from the National Archives, Colchester papers PRO 30/9/10/53). There are maybe a couple of very old cherries (the variety May Duke was the main one planted by Baron Colchester) and several plums (greengages?), espaliered apples and pears as well, which seem to match the locations from 200 years ago. Is it feasible that they are the original plantings? The magnolia on the outside wall to the south is also in the place marked on the plan. Clearly, many of the old trees have gone, but it is tantalising to try and match the plans with what is now in the ground.

This is one of the big old cherries:

and this is a plummy thing which looks like it is in the location where a greengage was in about 1810:

This I'm less sure about. At first sight I thought it was some kind of Sorbus, possibly the Wild Service tree, but it looks more like a Clammy Locust (Robinia viscosa). If so, this would have been a later planting to take the place of the earlier fruit trees that were in this spot.

and this is the bark of it: