First the no: The official currency of the UK is the pound Sterling. Shops and service providers, as a rule, only take Sterling. If you use a credit card, regardless of the currency in which you pay your bills, the card will be charged with sterling and your final credit card bill will reflect currency exchange and whatever fees your issuing bank levies on foreign exchange.
And now for the yes: Some of the UK's bigger department stores, especially the ones that are tourist attractions in themselves, will take Euros and some other foreign currencies (US Dollar, Japanese Yen). Selfridges (all branches) and Harrods will both take Euros at their ordinary cash registers. Marks and Spencer does not take foreign currency at the cash register but it, like other stores popular with visitors, has bureau de change - where you can readily change money - in most of its larger stores.
Lately, I've also noticed that pay telephone boxes in London and some other popular tourist spots, have started accepting Euros too.
If you are thinking of spending Euros in London or elsewhere in the UK, keep in mind that:
- Exchange rates calculated at the cash registers by the stores that take Euros may not be the most beneficial or may be out of date.
- Shop assistants are not really accustomed to taking foreign currency and your transaction may take longer than you'd like.
- Those stores that do take Euros will generally only take Euro notes - they will not take coins.
- You will have to pay for your goods using one currency or another. You cannot pay for part of your purchase with Euros and part of it with pounds Sterling.