Robert Lambert was on the rough end of some refereeing controversy in his first appearance as wildcard at the British Grand Prix.

The King's Lynn Stars ace saw his night start with bike problems and was the thrown out of a race for being the cause of the stoppage which the fans in the stadium could hardly believe.

Poland's Bartosz Zmarzlik won the showpiece event in Cardiff in front of thousands of fans at the Principality Stadium with Great Britain's Tai Woffinden runner-up – but he extended his lead in the title race to a staggering 20-points with five rounds remaining.

Woffinden, 28, now leads the standings on 81 points with his nearest rival ex-Wolves team-mate Fredrik Lindgren back on 61.

Woffinden admitted: 'It's job done as far as I'm concerned. Yes it would have been nice to win it but it's awesome to be 20 points clear at the top of the standings.

'That's the main thing as far as I'm concerned. Every single GP is another stepping stone to the ultimate goal of winning my third world title.

'I've not won anything yet. I won't be happy until the final race and mathematically I can't be caught. Speedway can be a cruel game, it can change in the click of a fingers.

'The crowd were once again incredible at Cardiff. The support I get from the British fans is simply unbelievable. It's a huge buzz and I'm pleased I could do a good job for them to thank them for their backing.

'I've just got one message for the fans: Speedway is coming home!'

Norfrolk ace Lambert, meanwhile, was left to reflect on what might have been – and he should simply put it down to one of those nights where everything went against him.

Scorers: Bartosz Zmarzlik 19, Tai Woffinden 16, Maciej Janowski 12, Greg Hancock 12, Patryk Dudek 10, Przemyslaw Pawlicki 10, Craig Cook 9, Emil Sayfutdinov 8, Fredrik Lindgren 7, Chris Holder 7, Artem Laguta 6, Matej Zagar 6, Nicki Pedersen 6, Jason Doyle 5, Martin Vaculik 3, Robert Lambert 1, Dan Bewley 0.