You'll be hearing a lot this summer about how Britain is heading back to the 1970s. That decade is all the rage as we swelter like it’s 1976 and memories are dredged up of a boiling summer when kids drove Chopper bikes across dried-up rivers and adults with crimson arms and blistered necks queued to get water from standpipes. Also, as Andy Burnham moves closer to Downing Street, doom-mongering Thatcherites are delivering siren warnings about him planning to drag us back to the Satanic Seventies