What is the rarest/unknown fruit native to Britain?

What fruits are unknown, or varieties/hybrids of fruit that are not well known in the UK but native to the UK?

 

Plymouth Pear (Pyrus cordata)?
Domestic pears and apples are not UK natives.
Some of the bilberries and similar.

 

Lovely fruit to pick in the wild if one has the patience, but very frustrating to grow for me! Could never get the soil quite right for them to take off like they do on the local moors and I can't imagine how many plants one would need to get a consistently decent crop!

Nick

 

@Nikolaos

I think they are fussy as to the conditions they like. I have never heard of anybody cultivating them.

 

I see them available as dried fruit from time to time @NigelJ, the price seems to typically reflect the difficulty of picking them! Yeah, I do wonder if they are picked from wild bushes or cultivated, I imagine the former is more likely...

Dried Bilberries 8 oz (226 g) Bag Organic | Piping Rock Health Products

Nick

 

Not rare, but we have Dewberries and wild Gooseberries locaĺly, and nobody else appears to either notice or pick them.

 

Not sure if my memory is serving me correctly, but I am sure I read somewhere that the only native fruit is the Gooseberry. Native as in found only here.