Babyshambles singer and rehab star Pete Doherty treated shoppers in Reading, England, to an impromptu performance in a music store, but the gig was cut short when the rocker snapped a string on the shop’s guitar.The former 29 year old Kate Moss boytoy picked up one of the instruments in the Music Man shop and went into a rendition of his hits, but Doherty’s energetic show was halted when he got carried away and accidentally broke the G string. But despite the breakage, store owner Peter Sirrell was delighted with the star’s surprise appearance.He tells British newspaper the Daily Mirror, "He had a whale of a time. he even asked me to put by a $300.00 guitar for him and he said he would be back in later to pay for it."