The event saw victories for Alex Gregory and Mo Sbihi in the men’s pair, Sam Townsend in the men’s single scull and, in the women’s single scull, a commanding success for Vicky Thornley.

Triggs Hodge, who rowed with Gregory in winning his second Olympic fours gold, finished 13th in the single scull having missed a year because of glandular fever, and Watkins – who has taken a three-year break since winning the double sculls with Katherine Grainger – was 12th in the women’s single.

Buckinghamshire-born 36-year-old Triggs Hodge, who said earlier of his comeback that he was taking things “day by day and step by step and if all goes well I’ll be in Rio and able to contribute”, pronounced his efforts in foggy but flat-calm conditions as “all right.”

Watkins, 32, who has given birth twice during her time away from the sport, said: “It felt really good coming away for the weekend and competing and every time I scull I know that I'm getting faster every week.

"But I am still a long way from the finished product."

Gregory, of Leander RC, and Molesey’s Sbihi finished six seconds faster than their nearest opposition – the Leander pairing of double Olympic champion Pete Reed and Constantine Louloudis.

All four men were part of the 2015 World Championship-winning men’s eight, as were George Nash and Will Satch who came home third.

“I have been racing 5ks here since the juniors in 2003 and there have only been two or three that I would say that I got right,” said Gregory.

“This was up there.

“As you are racing, because it’s against the clock, you don’t know how well you are going.

“You have to base it all on experience and the perception you have of your fitness levels.”

The top seven finishers were from the national squad with Leander’s William Warr and Matt Rossiter topping the non-squad list in eighth place.

Thornley, from Wrexham, underlined her sculling pre-eminence in the British squad by winning the open women’s single in 20:01.85, more than 15 seconds faster than the London 2012 champion with whom she won European bronze in the double scull last season, Katherine Grainger.

Grainger, who will turn 40 on November 12, clocked 20:17.16, just ahead of Melanie Wilson, timed at 20:17.55.

“That is a good start,” said Thornley.

“It’s what I would have expected of myself to be honest.

“It’s a long time since I’ve done a 5km trial as I was ill at the time last year and it is very much a fine line with pacing in this kind of race.

“Mind you, I had Katherine behind me so that was a good marker.

“In a race like this it’s easy to get to the bend [in the course] quickly and then die after that."

Polly Swann, who won world and European titles with Helen Glover in the women’s pair, was also making a comeback having missed last season with injury, and finished eighth.

Reading’s Olympian and World medallist Sam Townsend won the open men’s single scull title in 18:41.01, ahead of Leicester’s Jonny Walton, who clocked 18:55.48, John Collins, who was timed at 19:02.16 and 2012 Olympic bronze medallist Alan Campbell who recorded 19:07.06.

Richard Chambers won the men’s lightweight single scull in 18:51.33, holding off the challenge of his brother Pete who finished in 18:58.06.

The women’s lightweight scull was won by Imogen Walsh in 20:14.19, with London 2012 lightweight double sculls champion Kat Copeland second in 20:37.23.

The assessment was the first of three which will be held in the build-up to Rio, with the others due to take place on December 19 and February 27 to 28.

The GB Rowing Team Olympic Trials will then be staged at Caversham in March.

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