Great British high streets are in crisis. Shoppers are deserting them and retailers are blaming the plague of ecommerce. Chains from John Lewis to Marks & Spencer are closing stores, while many, such as HMV, seek urgent rescue from digital-induced oblivion.

The answer, according to some retailers and politicians, is a digital sales tax. Dave Lewis, the Tesco boss, has suggested a 2 per cent levy on web sales; other, more desperate players, have called for a 20 per cent tax on companies generating more than 20 per cent of sales online.

In reality, a digital sales tax is simply a nostalgia tax, an attempt to turn back the clock by those who have missed the ecommerce revolution slowly unfolding before their eyes since the