Belsize Park landed a big blow in the fight for promotion in London North-West Division Three, with a sterling defensive display laying the foundation for a 30-5 bonus-point victory over rivals Welwyn, who left empty-handed.

BP were looking for revenge after throwing away a 20-point lead in Welwyn earlier in the season, but tries from Jon Corellis, Miran Serdarevic, Richard Wilson and Will Allen ensured they went level on points with second-placed Welwyn.

An early penalty from Kiwi full-back Jeremy Burton settled the nerves, but Belsize found themselves one try down shortly afterwards after some soft tackling.

This would be Welwyn’s only score of the afternoon, however. Centres Chris Dan and Corellis were titanic in defence, and it was the marauding No12 Corellis who scored the home side’s first try, bulldozing his way to the line to take Belsize into the lead after 20 minutes.

Belsize never looked back and Serdarevic put daylight between the sides, carrying the ball 30 metres after a sharp line-out, leaving three defenders on the deck and two hanging off his shirt as he finished under the posts.

If the first half was characterised by individual brilliance, the second period was more of a defensive team effort – with the exception of Wilson’s well-taken try, which extended the lead further.

BP had to endure pressure from a powerful and structured Welwyn side, giving away a number of penalties in their own 22 - and the referee had no option but to reduce them to 13 men, showing yellow cards to captain Tom House and the outstanding Adam French, who shared the man of the match award with Dan Steadman.

Yet the numerical disadvantage only proved to be a catalyst for Belsize, and a combination of superior organisation and some good fortune ensured their defence remained watertight for the remainder of the game, frustrating the opposition, who made some questionable decisions in attack.

The scrum was a consistent platform for Belsize to launch both attack and defence and the addition of Michael Downes to the front row and Chris Dan to the back row with men in the bin allowed the momentum to be maintained.

With five minutes remaining, the reliable boot of fly-half Wilson broke up play and No8 Seb Dunnett raced downfield in a characteristically dogged counter-attack, relieving the pressure and allowing Allen to touch down in the corner and secure the bonus point.

Belsize visit fifth-placed Hackney on Saturday.