This is a wonderful apple! I've got a tree of them and just eaten the first of this season's crop. It's both sharper and sweeter than the well known Cox. It doesn't look anything much and it took 7 years to start fruiting but it's worth it.
People have been discovering apple varieties for a long time. In some ways it's quite easy because they are fairly promiscuous and different varieties cross with each other. Some of the pips get to be seedlings but few go on to produce wonderful fruit. Worse still, an apple tree grown from seed takes ages to produce - and the plant can get annoyingly large. Most of them don't make it but about 300 years ago, a Dr Ashmead in Gloucester found this variety of apple. Its career was a bit slow to take off but nowadays it's even grown in America.
I tried one from a Farmer's Market stall in Cheltenham and was so impressed, I decided to grow my own.