WGC won their sixth successive league away victory to move to third in the SSML Div 1 title race and close up further on the sides above them.
They have four games in hand on Risborough Rangers, who have moved second and three on leaders and neighbours Hatfield, who lead the Citizens by seven points.
Again WGC's squad strength was shown, as they were without suspended trio - Joel Norris, Craig Arnott and Jack Dekanski - for this one and have goalkeeper Joe Croft sidelined with cracked ribs and bruising injuries. Croft hopes to be back within the month.
For the opening 20 minutes, London Lions made this a really competitive affair and had the first opportunity on goal, Benji Weinberger turning well but struck his effort straight at WGC coach Chris Benton, who was deputising in goal.
In nine minutes good WGC build up saw Aaron Cato do well to keep the ball in play and set up Marc Arnott, deputising for his brother, to put Jason Caswell clear. The forward went down under challenge from keeper Mario Cenolli, but referee Ballantine booked the Citizens' striker for 'diving'.
It continued to be a tight affair until just before the half-hour mark, when Sean Brettell freed Caswell wide on the right and his driven cross took out the entire Lions' defence for Arnott to net a tap-in on the far post.
The Lions responded with Weinberger again making space cleverly to create a chance, but again struck it straight at keeper Benton.
Then on 37 minutes, the home side truly gifted WGC a second. Keeper Cenolli, trying to find his full-back Lawrence Judah with a clearance, only found Aaron Cato instead and the WGC winger punished the mistake heavily, driving his effort straight back past the keeper for 2-0.
WGC made a change at the break, replacing full-back Jay Lovell with midfielder Perry Stellon and soon created a chance for a third, Arnott laying it on for the outstanding Daryl Smith, but he scuffed his shot wide.
Moments later, Benton was brought to his first real save of the game, making a fine block with his body as Lions' dangerman Max Kyte broke clear.
WGC full-back Sam Perrin made a forward burst and put over a low cross that neither Arnott nor Caswell could make contact with, as it shot across the goalmouth.
With 12 minutes to go, WGC ensured the victory was secure, as Smith rose perfectly to a Brettell corner to head down into the Lions' net for the third.
Lions were reduced to 10 men when full-back Judah received a second yellow card for a heavy foul on WGC substitute Reggie Ross.
There was still time for Caswell to head a left-wing cross from Ross against the foot of a Lions' post two minutes from time and for a low drive from home striker Kyte, that beat Benton, to suffer the same fate, deep in stoppage time.
WGC: Benton, Perrin, Kenna, Costain, Lovell (Stellon 45), Cato (James 82), Cifuentes, Smith, Brettell, Arnott (M) (Ross 72), Caswell.