Was in Sainsbury's today and noticed a seperate rail in the middle of the clothing aisle (not with the latest school uniform) that was full of school dresses, the checked ones for primary schools. There were different colours; red, blue and yellow, maybe green too. There were single ones at £1.05 and twin packs for £1.80. I bought 2 twin packs for the next few years! Can't see it online so assume it's in store only.