This was the team's third single on the EMI label, their sixth overall, and the song that finally brought Chas & Dave to the attention of the British public. Backed by "The Banging In Your Head", it was the first of their releases to make the top fifty, peaking at number twenty.
As might be deduced from its title, this is a novelty song, "Gertcha!", a popular East End exclamation of disbelief - and sometimes a mild threat - being what the singer(s) old man would utter when riled. Old man in East End parlance referring to one's father.
Unsurprisingly, "Gertcha" was used in a TV commercial for beer.
Suggestion credit: Alexander Baron - London, England, for above 3