Fans had already started to file into the venue for the gig when bosses alerted them to the change of plan via

In a series of messages, a representative wrote, "We're very sorry to say that tonight's concert has been cancelled due to Tony Bennett being taken ill. Apologies to disappointed fans.

"We will contact all ticket-holders as soon as we have any more information. We would also like to wish Tony a speedy recovery."

The statement had some devotees worried about the 88 year old's ailing health, but he subsequently took to his own Twitter page to assure fans he was just suffering from the flu.

He tweeted, "Sorry to not be singing in London tonight. I love my fans in the UK and appreciate all the well wishes to get over this flu quickly."

Gaga also reached out to her followers to insist the veteran entertainer will be just fine, and promised to return another time.

She wrote, "Hey everybody! Don't worry about Tony, he's ok! That's just showbiz sometimes. We'll catch u next time, we got you (sic)!"

The cancellation took place just one night after the Cheek to Cheek collaborators performed for Prince Harry during their first London date, which had been held as a charity benefit to raise funds for the British royal's children's foundation, WellChild.