Bill writes
Thank you Mike and June for your replies.

I used to have a pear tree in the garden of one my previous houses, and
it became huge and unmanagable after 10-15years. In fact, I notice
the current owners have now cut it down when I drove by the house a
while back.

Can crab apple trees grow as aggressively as pear trees?

Crab apples can grow quite large. The embryo fruit looks a bit large for
a crab apple at this stage of the year.

Eating apples are normally grafted on to a rootstock which reduces
vigour and overall size.

Your tree could be a pear or an apple, but apples are far more
frequently planted, so it's more likely to be that.
--
Kay