In the commentary, broadcast on Tuesday, Mercer said: “I suppose the one thing that I have at the back of my mind at the moment, is Laura mobile enough around the court?

“Perhaps a little puppy fat at the moment, the sort of thing you’d expect her to lose as she concentrates on tennis full-time.”

Robson won a place in the semi-finals of the Wimbledon girls’ singles after beating fellow Briton Tara Moore, 17, this afternoon.

Speaking afterwards, her mother, Kathy, said: “We don’t care. Who’s some BBC reporter? I don’t know him, he doesn’t know us.

“The important thing is that she’s in the semi-finals.”

His comments went out live on Tuesday for viewers who used the BBC’s interactive red button service.

A BBC spokesman said: “David has apologised to Laura for any offence caused.”

Mercer, a former solicitor, was a Welsh junior doubles champion in 1968 and umpired the Wimbledon men’s singles final in 1984.

As news of the furore hit the All England Club today, he was eating lunch in the press canteen.

Mercer said: “I wouldn’t call it a debacle at all.

“We are all sitting down later and going through the transcript so that I can actually see exactly what I said and I can then take a view on it.”

Robson has overcome flu-like symptoms to keep her hopes alive of repeating her 2008 title success.

She was knocked out of the women’s tournament in the first round after losing to fourth seed Jelena Jankovic.

Robson has previously apologised herself for making disparaging comments about women tennis players in a magazine article for Vogue.

Wimbledon was hosting the women’s semi-finals this afternoon while preparing for full-scale “Andymonium”.

Fans were already camping outside the All England Club for a precious ticket to see Andy Murray’s crunch semi-final against world number one Rafael Nadal tomorrow.

His odds of claiming the title were slashed after he beat Jo-Wilfried Tsonga yesterday and six-times winner Roger Federer crashed out.

Not since the 1930s has Britain been more likely to be toasting home success on Sunday, bookmakers said.

The fourth seed battled past big-hitting Frenchman Tsonga 6-7 (5-7), 7-6 (7-5), 6-2, 6-2 in a tense encounter on Centre Court last night to set up his blockbuster last-four clash with the 2008 champion.

In previous Grand Slam encounters with Nadal, Murray has beaten the Spaniard on his way to finals at the US and Australian Opens.

The 23-year-old said: “I know it’s going to be an incredibly difficult match to win, but it’s one I believe I can win if I play well.”

He was preparing for the showdown with a “boring” day watching television and walking his dog, Maggie.

Bookmaker Coral slashed the odds of Murray winning the title from 7-2 to 9-4. Nadal is favourite at 11-10.

As Murray homes in on the final, fans are paying record prices for tickets to Sunday’s match.

Ticket website viagogo reported a 150% surge in interest in recent days, claiming prices could reach £22,000 (€26,740).