Instructions:20% discount off entry to attractions around the UK (large number London based), tours & even food restaurant bills!
Check the homepage for a full list of locations that this printable voucher can be used at....
"Sightseeing in London is more affordable with Discount Britain. With a 20% discount at top London and UK tourist attractions including London Zoo, London Aquarium, London Dungeon, Thames Cruises and Kew Gardens, and a 20% discount at popular London restaurants including Planet Hollywood, Bella Italia and Eds Easy Diner, saving money with Discount Britain has never been easier. So if you are a tourist visiting London or the UK and dont know what to do, or you want to visit London and save at the UK's top tourist attractions, make sure you take your Smartsave code number with you."
(Minimum spend set at a penny due to the widely varying prices at different locations)