TV and stage actress Juliet Stevenson says it was "uplifting" speaking to members of the public donating to today's telethon.
She said helping take donations had made her aware of just how much British people care about what's going on.
She spoke to ITV News Correspondent Rageh Omaar at the event:
More top news
After the Indiana polls close, ITV News asked Ted Cruz supporters if they could back Donald Trump as the Republican presidential nominee.
With his massive victory in Indiana, Donald Trump can now not be stopped from becoming the Republican nominee.
Donald Trump is predicted to win the crucial Republican Indiana primary, US media have projected.