Negus was a game opponent, but Harrison looked fit and put together some great punching sequences in the six-round heavyweight encounter at Wembley Conference Centre.

Harrison took advantage of his greater size and reach to outbox the Milky Bar Kid and earn victory by 59 points to 55.

But the fight centred around a controversial fourth round.

The Olympic champion appeared to illegally hit Negus while he was down on one knee, prompting him to spit out his gum-shield and try to head-butt Harrison.

Believing it was a low punch, the 30-year-old lunged forward in a scene more reminiscent of a bar-room brawl.

The referee struggled to separate the two fighters but after sending them both to their corners, he allowed the fight to continue without docking any points.

The crowd in north London was mainly supporting Harrison - but there was a big contingent of Negus fans too.

Afterwards, Harrison told BBC Sport: "Once again Harrison performed and I am just going to keep rolling on.

"I have got nothing to prove to anyone.

"He was a live opponent and got dealt with like all the others.

"If he did not use some of the illegal Queensbury Rules, he would have been taken out of there.

"People can say what they like - I don't really give a hoot."

Negus, who is a minder by day, added: "A better boxer beat a better fighter today but he was not as good as I thought he would be.

"My mum hits harder than that."

In another bout, Robin Reid had to settle for a unanimous points victory after flooring Argentina's Francisco Mora twice as he successfully defended his WBF title for the fifth time.

Reid, the former WBC super-middleweight world champion from Runcorn, put Mora down with a right upper-cut in the third round and floored him again with a classic right hook in the sixth, but both times the durable challenger climbed up.

And Bristol's Glenn Catley, another former holder of the WBC super-middleweight title, ended a run of four successive defeats in title fights abroad by narrowly out-pointing Russia's Vage Kocharyan in their eighth-round non-title fight.

But Catley, boxing in Britain for the first time for four years, struggled to impose himself on the visitor and had to settle for a narrow 77-76 decision.