Jules O'Dwyer and her well-trained pup Matisse bounded to victory in 2015 – but controversy quickly followed.
The incredible double act took on acting roles during their routines, starting as a dog catcher and a stray during their first audition, then as a toy maker and toy in the semis.
During the final, they pretended to be a policewoman and sausage thief along with three-legged pooch skippy as they beat Cor Glanaethwy and Jamie Raven to win the cash prize and a slot at the Royal Variety Show.
However, TV regulator received over 1,000 complaints after it emerged Matisse and Skippy were not the only dogs who had performed in their act.
Jules' other dog, Chase, also performed in the live final of the show, but viewers were not told that the dog scaling a tightrope in the biggest trick of the night was not Matisse.
The dog trainer admitted she had duped viewers during an appearance on ITV's Lorraine, telling the host: "Matisse is a little bit afraid of heights so although he could officially do it, Chase is the action dog, so he plays the double for him."
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Fellow dog act Ashley and Pudsey, who won the show in 2012, mocked the pair on Twitter by, writing: "Stunt double? Pah!" along with a snap of the adorable pooch on his back legs.
Sickeningly, vile trolls sent death threats towards Matisse on social media and Jules admitted she feared for her dogs' safety.
"The reaction is upsetting but my only worry is my dogs’ welfare and safety. I’ve always been worried about them," she told Daily Star.
"I never leave the dogs unattended. I don’t trust anybody. I’m pretty strict as it is. I’m a bit over the top.
"They’re my babies and if anything happens I’d be distraught, as would my daughter. They’re her little teddy bears. They’re our family pets."
Jules also stated her intention to increase security at her home - but said her biggest protector was her 60kg German Shepherd.
Britain's Got Talent bosses were forced to issue a grovelling apology after admitting Matisse the dog used a "stunt double" for part of its act in the final.
A BGT spokesman said: "The audience had previously seen from Jules’ semi-final routine that she works with a second dog Chase alongside Matisse. For the final performance, as Jules has said publicly herself, Chase completed the tight-rope walking section of the act.
"During the competition viewers have seen that Jules' act involves a team of dogs, including Chase and Skippy, alongside starring dog Matisse, to perform her unique mixture of dog agility and story-telling. We are sorry if this was not made clearer to the judges and viewers at home during their final performance."
In August 2015, Ofcom ruled that BGT had misled the public, acknowledging that ITV did not intend to deceive viewers, but did break the ruke which states that "broadcasters must ensure that viewers... are not materially misled about any broadcast competition or voting"
No formal action was taken against the act and they still performed in the Royal Variety Performance under a new name, Jules, Matisse and Friends.
Speaking of her stint on stage at the Royal Variety Performance, Jules revealed: "It was a bit daunting going to the Royal Variety and performing for such an important audience, with eight dogs on a small podium!
"It was the first time I was actually really nervous. Luckily for me, my dogs didn’t let me down and they pulled it off, so I was very relieved. It was very special."
A year after their victory, Jules said she has "gained a lot of confidence" but had never been a fan of the limelight.
She explained: "I’ve always been very low-profile and consider myself to be really normal. I’m not one to push myself into the spotlight so that was new for me, that was a real learning curve.
"To have fans running up to you and wanting selfies from the dogs. That’s taken a bit of getting used to.
Jules added: "On the whole, it has been really positive and surprising how many people appreciate what I’ve actually achieved with my dogs and that is of course, fantastic."
She used some of the £250,000 prize money to marry her girlfriend, Marie France, and Matisse got to have the first dance.
"The money meant we could have a wonderful day together. For the first time in a long time we actually had time together because I am usually away working" Jules told The Sun.
"After everything we went through we just decided that we love our life together so let’s make it more permanent. We’ve been together 11 years so it was about time we got round to it."
Jules and her border collie currently live in Tongeren, Belgium - and it is unclear whether they are still performing.
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