Pete Townshend has apologised to a seven-year-old fan he bad-mouthed for asking the grumpy rocker to smash his guitar at a concert in Ontario, Canada.

Jenny Costello was left crestfallen when The Who star singled her and her father out at a Hamilton show last week (19Feb13) after spotting her homemade 'Smash Your Guitar, Pete!' sign as he looked out into the audience.

In video footage posted online, the guitarist can be heard saying, "Go away with that sign please, just go away with it, just go away with it. Don't bring your children... I want to tell you two words but I can't because you've got a child there."

Townshend then mouthed the words "F**k off!" at Costello's father, prompting him to leave the concert early with his daughter.

After realising that little Jenny was actually a fan and her sign was just a token of her appreciation for Townshend's music, the rocker reached out to the seven year old by writing a personal letter to her, according to the Sun News Network, which read: "Apologies and condolences from my side, and very best wishes to you and your family."

The British guitar great is now hoping to meet the child and her father, so they can "put this behind us".

The letter continues: "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 sympathize with you both, and your daughter's mother, 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.

"I thought of sending someone to find you both and telling you I was not upset, but we were flying to New York straight after the show, and had no time to spare. I wish things had been different. It would have saved you from all this furor."

Townshend adds, "I thought your placard was fun (but) I had a job to do (to announce our musicians) and I didn't want to lengthen the show by trying to deal with you directly and in detail. 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."

Townshend is now planning to meet the Costellos in April (13).