Almost as intriguing was the South African’s work ethic, which apparently saw him knocking on doors all over Dundee and Broughty Ferry and as far afield as Brechin seemingly in the one day.

However, Dundee councillor Ian Borthwick today got to the bottom of the mystery salesman when he discovered that all the direct salesmen employed by Scottish Hydro Electric are from South Africa!

Mr Borthwick said he had raised the aggressive sales approach of the South African with the company after taking up a complaint on behalf of a woman.

Before Hydro Electric could reply, the councillor also had a visit from a South African salesman and found him to be quite cordial.

Mr Borthwick said, “I mentioned this to Hydro Electric when they got back to me and that’s when I was told that all of their direct sales force are from South Africa.

“It seems they couldn’t find the quality of sales person they wanted here so they employed a South African agency which identified many of their countrymen with work permits. Although the doubtful sales tactics of this one South African were a serious enough matter, it was funny to think that people have been reporting visits from him all over the place when it has probably been a variety of South Africans knocking on their doors.”

The South African who upset so many customers was one of two men sacked by Hydro Electric in the wake of the complaints raising a question about how they managed to identify him from amongst his countrymen.

Mr Borthwick said it seems they were able to pick the right man by following up the complaints. Each salesman is given a certain area to canvas and by noting the addresses of the complainers, they could tell who was eliciting the grievances.

A spokeswoman for Hydro Electric today said the sales people were “all university graduates working in their gap year”.