Here's the statement from Phil's FB page:
We unfortunately have to announce that Phil Collins’ performance at the Royal Albert Hall in London will be postponed tonight (June 8) and tomorrow (June 9). Phil suffers from ‘drop foot’ as a result of a back operation which makes it difficult to walk. He rose in the middle of the night to go to the toilet and slipped in his hotel room, hitting his head in the fall on a chair. He was taken to hospital where he had stitches for a severe gash on his head close to his eye and is recovering well. He will be kept under observation for 24 hours.
Phil sends his sincere apologies and thanks to fans. He has had a fantastic week at his first shows in 10 years, cannot thank people enough for their warm reaction and is excited to return.
These Royal Albert Hall shows will be rearranged for November 26th and 27th this year. All tickets for June 8th will be valid for November 26th and tickets for June 9th will be valid for November 27th.
He will carry on with this tour on Sunday in Cologne and then Paris before returning to London for his headline performance at Hyde Park on June 30th.
This is a video by a fan. It's the second night at Royal Albert Hall last weekend: