Text Santa, ITV's festive appeal to help six charities, culminates tonight with a special appeal show but throughout the day there have been fundraising events.
And stars of West End shows got in the spirit of things this afternoon, by singing Christmas carols in Leicester Square.
Here's our Arts and Entertainment Correspondent Lucrezia Millarini.
More top news
Dozens of women gathered on Westminster Bridge to form a human chain in a show of solidarity with the victims of Wednesday's terror attack.
In a wide-ranging Peston on Sunday interview, he said Parliament security needs reviewing and the PM's counter-terror strategy is flawed.
The terror attack carried out by Khalid Masood at Westminster that left four people dead lasted less than two minutes say police.