The 35-year-old’s career hung in the balance in April last year when he lost his British cruiserweight title to Viddal Riley — his second successive defeat in five months.

But he got back to winning ways in a low-key eight-rounder in December before climbing up off the deck twice to stop Jack Massey on Billam-Smith’s undercard in Bournemouth five months ago.

That dramatic turnaround victory earned him a fight with former WBO champion “CBS” at the top of this Zuffa Boxing show at Copper Box Arena, but he was a clear underdog with oddsmakers.

Clarke, however, made a mockery of that by stopping Billam-Smith (22-3, 14 KOs) in an untidy scrap. After beating him twice in the amateurs in 2016, Clarke completed his hat trick a decade later.

The stoppage, which came from referee Lee Every after 1:24 of the seventh, was a controversial one as Billam-Smith, who had been down twice, was on his feet and seemingly able to fire back. His trainer Shane McGuigan was apoplectic with the decision.

Regardless, Jamaica-born Clarke (13-2, 10 KOs), the former lorry driver-turned-Team GB Olympian, claimed the biggest win of his career.

These two had never seemed to be on a collision course until Clarke’s victory in Bournemouth changed everything and tempted Zuffa to make this all-British clash.

Once it started, it was clear that this was going to be an attritional affair. They got stuck straight in, but Every had to tell them to tidy up after just two minutes of the first. However, it was still scrappy in the second with lots of holding and resetting. Both were attempting to work on the inside whenever they got up close, but there was little rhythm.

Billam-Smith got through with a hook-cross combination in the second but Clarke responded with a thudding right hand which drew cheers from the crowd. It was more of the same in the third, with only snippets of clean work interspersed among the wreckage. After a legendary firefight with Ryan Rozicki in his last outing for Billam-Smith, this was a more grinding battle.

Clarke was attempting to land with big rights on the way in before smothering the response — and it was working. Early in the fifth, he found a home for a right hand which seemed to momentarily wobble the former world champion. That shot set the tone for an entertaining round as they began to work behind their jabs instead of chest-to-chest.

In the sixth, Billam-Smith landed a right hand which seemed to hurt Clarke for a split second, but he just shrugged in response.

Then, with 30 seconds gone in the seventh, Clarke landed a right hand which sent Billam-Smith, The Ring’s No. 3 cruiserweight, down. He took his time to reach his feet but Clarke went straight back in for the finish

Billam-Smith went down again after wriggling free on the ropes but there would be no let up from Clarke, who was hellbent on closing the show. Another flurry was enough to convince the referee enough was enough.