The message
from Jaques d'Alltrades contains
these words:

While you're here, have you any idea of the name of an apple fitting
this description?

Small fruit.
Very early.
Magenta skin (all over) when ripe.
Crisp and sweet even when unripe.
Flattish, Tangerine-shape (and size) reminiscent of an overfilled inner-tube
Deep pit at the stalk
Less deep pit at the other end
Doesn't keep well.
strong 'fruity' scent

Could it be 'Discovery'?
'Discovery' is one of the earliest (August), is deep crimson and
roundish/flattish like a tangerine/inner-tube. Mine are bigger than a
tangerine, I would say but I think size varies with conditions, age of
tree etc.
I haven't studied how deep the cavity is - and have eaten mine now, so
can't check. Apart from size, the rest fits.
Janet G