There was a time, not so long ago, when the iPhone was a byword for exclusivity. Carriers fought for the right to offer it and queues formed outside the small number of shops which shone with its presence. Now you can buy the thing in Tesco. The UK’s largest supermarket, which pockets something like one of every seven pounds spent in Britain, will soon be making the latest versions of Apple’s iconic handset available on its MVNO, Tesco Mobile.