"He phoned up to see what it was all about as he had no idea something had been left in the handbag."
The man called in to the shop and collected the $275 cash which he said belonged to his 98-year-old mother, who resides in a rest home.
"The gentleman, who wishes to remain anonymous, was very surprised and grateful that we went to so much effort to find him," said Ms Sibbald.
"St John have a strong belief in their values, one of which is 'Do the right thing'.We are all very happy with the outcome."
Profits made at the Ingestre St shop, which opened in 2014, go towards local St John youth programmes, purchasing new ambulances and health shuttles, and buying vital new equipment.