Millie's Kiss (blue cap), running in the name of stablemate Mandarin Princess, wins the opener at Yarmouth from 4-6 favourite Fyre Cay (right)

Yarmouth was the scene of an unprecedented mix-up in British racing on Thursday when the 50-1 winner of the opening two-year-old race was later identified as her year-older stablemate who had been due to run later on the card.

Trainer Charlie McBride called the error a "genuine, honest mistake" which had come about due to him being delayed collecting the saddle and then rushing to tack up the horse in time for the race.

He said: "It's a genuine mistake and humans make mistakes. It’s an honest error and no-one stood to gain anything by it.

"I took a young girl who has been with me for two or three months to the races. She’s ridden both fillies and knows them both. After we checked them in we got some lunch and I sent her to get the two-year-old ready and I went to the weighing room to get the saddle.

"I like to weigh my horses out early but I had to wait over 20 minutes for the saddle. The filly was already out when I got back and as I was stressed and rushing I didn’t look that closely - I just assumed it was the right horse."

The mistake was only realised at the post-race sampling unit and after the weighed-in announcement had been made by officials, leaving the racecourse stewards with no power to amend the embarrassing result, which has been referred to the BHA.

McBride added: "They are two brown fillies and if you stood them together I’d be able to tell them apart straight away. I know both fillies but in the heat of the moment I didn’t look at the filly.

"In the paddock and after the race there were a lot of owners and people to deal with. It never dawned on me it was not the right horse."

Mandarin Princess had appeared to cause an upset when winning the 6f novice auction stakes for Newmarket-based McBride and jockey John Egan from 4-6 favourite Fyre Cay.

Charlie McBride: mistake was not spotted until after the weighed-in signal

However, when the horse was later identified at the sampling unit, where race winners are taken for a blood or urine sample, she was revealed to be Millie’s Kiss, a three-year-old stablemate scheduled to run in the fourth race, a 1m1f handicap.

An inquiry was called by the stewards, but no announcement regarding the race was made on course until 4.12pm, nearly 45 minutes after the mistake had first come to light and over two hours after the race.

In the meantime punters, bookmakers and those connected with the horses were left in a state of confusion and disbelief.

Stipendiary steward Tony McGlone told At The Races: “I've not come across this before. As with all horses they were taken across to the stables, scanned and then were allocated a box each.

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"Mr [Charlie] McBride was over at the weighing room and was slightly delayed and the stable girl had taken the horse out of the stables and into the saddling boxes. As he was in a rush, he put the saddle on, the horse ran and won.

“We then sent the horse for routine testing as normal and the veterinary officer scanned the horse and found it to be the incorrect horse. We've inquired into the matter and it's possibly a genuine mistake.”

He added: “We've referred it to the BHA for further consideration. I think they've got 14 days to lodge an appeal to the winner. The system does work but like all things it's not fail safe.”

Such a situation has not occurred on a British racecourse since the introduction of microchip identification in 1999, and a full investigation is set to be launched by the BHA.

'Result cannot be amended'

A BHA statement said: “The incident at Yarmouth has been referred to the BHA’s head office in order that we can carry out an investigation, in accordance with our rules. Since we introduced the microchipping identification system an incident such as this is, as far as we are aware, unprecedented.

“The issue had not been established until after the result had been made official. After the weighed-in has been declared on the racecourse, the result cannot be amended by the stewards.”

It continued: “The responsibility lies with the trainer to present and run the correct horse in the race. Having said that, and while we have not seen an incident of this nature in recent times, we will of course determine what steps need to be put in place to prevent it from happening again. We sympathise with the betting operators and betting public who have potentially been affected by this incident."

'I thought the lads were taking the mickey'

Egan, who had partnered the McBride-trained horse, questioned why the result had not been amended on course.

"I didn’t know [about the mistake] until the fourth race, I thought the lads were taking the mickey," Egan told ATR.

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"At the end of the day we’re all human and mistakes happen. I feel most sorry for Charlie and I’m sure there’s no-one more disappointed. There are worse things in the world that happen and we’ll all get over it and move on.

"I’m surprised the stewards didn’t make the race void or disqualify the winner. It’s the wrong horse in the wrong race and it seems very simple to me. I can’t understand that rule."

Layers stunned

On-course bookmaker Dan Hague said: “It's a total embarrassment – it shouldn't really happen in this day and age. As bookmakers we have to abide by the 'weighed in' announcement otherwise there's no end to the business.

“There has to be a cut-off point and they've weighed in and then this has come to light. I took a £1,100 bet on the favourite [Fyre Cay] from a regular customer and to be fair to him he'd said they've weighed in and that's it. I might sort an ex gratia payment with him but how far do you go as I've paid out £400 on the winner?

“You've got to think it's a one-off, but it can never happen again. It's a very sad day for British racing.”

If you are interested in this, read more:

What action the bookmakers are taking . . .

That's not my name: other cases of mistaken identity