John Niven's debut play explores rivalry between the two British bands who vied for the No 1 spot in the charts in 1995 It was the great Britpop showdown in the summer of 1995, billed as a contest between cheeky chaps and lairy lads. Thirty years on, a new play is to revisit the fierce rivalry between Blur and Oasis when both British bands put out a new single in the same week and competed to grab the No 1 spot in th…