The Leigh Park bare-knuckle boxer suffered the break after falling awkwardly having been knocked down in the third round for the first time in his career at the event staged at London' s 02 Indigo.
Yet, somehow the 38-year-old continued in his quest for British title glory, defeating Thomas with a KO win in round four with his opponent stretchered out of the ring after sustaining a horror leg break.
Parker, who took his bare-knuckle record to 6-2 with his title win, admitted he had to 'go to the trenches' to pull what was looking an increasingly unlikely win out of the bag.
And he insisted there was no way he was going to let his Pompey travelling following down by not bringing the belt home.
Parker said: ‘It means everything (to get the British title). It was a hell of a shot to win it, if you watch it back and back and back, I finally got the KO win that I’ve always wanted to get in BKB.
‘I’ve had a few stoppages but that punch was just a worldie of a punch, it’s one of those you always look to land.
‘To be honest, I got put down in the third for the first time in my career. I went back to my corner, my corner just said to me it was all over nothing, we had to go for it and there was no mucking about with it.
‘I think Billy (Bessey) my coach started waving his arms up and down and the crowd went absolutely crazy - there was no way in the world I was letting those people down. I just went out there and I just pulled it out of the bag.
‘I had to go to the trenches, as such, in that fight. My family, often my wife especially, she says to me I don’t get angry enough but I think the anger came out when I was against the wall.
‘Everything was against us going into the fourth round, we’d just lost the third, we were probably two rounds down there. He won the first, I won the second and he took the third.
‘I’m probably two rounds down going into the start of the fourth and I just had to go for it. We got him out of there and it was fantastic.’
Parker says the adrenaline from such a big fight occasion ensured he was able to carry on despite breaking his ankle.
In fact, he only started feeling pain from the area yesterday - and decided to get it checked today.
After such a bruising battle, Parker remains unsure of what the future might hold for him having achieved his ambition of becoming a BKB British champion.
He said: ‘He just went over awkwardly on his leg, but to top it all off I’ve broke my ankle.
‘When I went down I went down exactly like him and broke my ankle. It’s unbelievable, you couldn’t write it. Two fighters broke their leg in the same fight.
‘The adrenaline takes over. I was walking around yesterday on it and I’ve just had it checked out now and that’s broken - I don’t do things by halves.
‘Who knows? (what comes next). I’ve gone as far as I think I can go. I’m not sure but we’ll see (what he does next).’