15 alternative things to do in London — all except one are under £20

London is full of underrated and ‘hidden gem’ spots – you just need to know where to look (Picture: Getty Images)You’ve got your selfie outside Buckingham Palace. You’ve marvelled at St. Paul’s Cathedral. You’ve stuffed your face with pasties at London’s oldest food market.
You look up to Big Ben to check the clock, only to realise you’ve still got loads of time to kill in the Big Smoke.Tourist traps aside, alternative London is where it&rsq