Pete Townshend has reportedly written a letter of apology after telling a seven-year-old girl – and her over-enthusiastic dad – to "fuck off".

The grumpy moment took place on 19 February, during the Who's concert in Hamilton, Ontario. According to the Toronto Sun (via NME), 50-year-old Eric Costello's daughter was sat on her father's shoulders waving a placard that said "Smash Your Guitar, Pete!" But as is made clear in a fan's video, the kid was not all right. Something about the scene made Townshend furious. "Don't wave that sign," the guitarist said, on the microphone. "[And] don't bring your children … I want to tell you two words, but I can't because you have a child on you." He then mouthed the words "fuck off".

"Nobody talks to my seven-year-old daughter like that," Costello later told the Toronto Sun. "I expect a 70-something-year-old man to respect the fact there's a seven-year-old girl standing in front of him." Although Costello said he understood that Townshend may have thought he was "using" his daughter to get closer to the stage, "that is not what happened at all". His daughter is a huge Who fan and was the one who painted the sign. "I'd like [Townshend] to know in some small way he broke a little girl's heart."

Costello's comments had an effect. Townshend may have been irritated at being called "70-something", but with the help of a local radio DJ, the 67-year-old sent an apology to the Costellos. "Apologies and condolences from my side," he wrote. "I asked my friend Mike Tyler to find you so I could tell you that I am so sorry the story about us blew up the way it did, but also to tell you that I sympathise with you both … and that I am most certainly not angry … I was not angry on stage either. I was in rock star mode, the big mouth."

"I could have handled it differently," he went on. "I thought your placard was fun … I was also worried that your daughter looked a little frightened as the crowd started to follow you down the aisle. The ushers should not have let you leave your seats and walk forward. All that said, you did nothing wrong … [I hope we can] meet and be friends and put this behind us."

Townshend plans to reconnect with the family in April.