Carol singing starts in Trafalgar Square tonight between 5-9pm and every evening (except 20 December) until 22 December (free).
Tuesday: The Grant Museum screens The Blob in the Darwin Lecture Theatre, Malet Place WC1E 6BT from 6.30pm (free).
The Pigs Ear Beer and Cider Festival starts today at the Round Chapel Hackney – till Saturday (entry £4, Camra members £2)
Wednesday: There’s a talk about ‘the quest for a clean drink‘ at The Chemistry Centre, Burlington House, Piccadilly from 6.30pm (free).
And another talk about Edible Architecture by Food Historian Gillian Riley at the Doodle Bar from 7.30pm (free).
Go to the Etsy Christmas Grotto for ‘re-gifting’ and gift swapping at the Trampery, 13-19 Bevenden Street (2 min walk Old St tube), London, N1 6AA from 6.30-10pm (free).
Friday: Free ice-skating and treats plus a Christmas market in the Scoop, More London from 10am-6pm (Friday-Sunday).
Saturday: The Green and Ethical Christmas Fayre is on Clapham Common between 10am-3pm.
Hear Christmas Gamelan Chimes in the Clore Ballroom at Royal Festival Hall from 4.30pm (free).
Sunday: The Grand Union Youth Orchestra play world music at Rich Mix between 10am-2pm (free).
Want more? Have a look at our constant guide to Free Things To Do In London.
What did we miss? Let us know in the comments.