That was after Bees had bossed the first half but failed to turn their pressure into a single point.
The visitors were guilty of missing several kicks at goal, winger Ian Briggs stepping up first before scrum-half Jack Jolly took over, making a welcome return to action following a long lay-off due to back surgery.
But Jolly proved no more successful as both sides repeatedly cancelled each other out in a game that was heading towards a remarkable scoreless stalemate.
Lions seized their chance to break the deadlock after Bees were reduced to 14 men on 67 minutes when replacement Kinsey Stoddard was given a yellow card.
Lions pressed home their extra-man advantage when they spun the ball wide for winger Luke Veeble to score in the corner on 71 minutes.
But Bees battled back and were presented with a chance to narrow the gap with a penalty on 74 minutes.
Jolly’s kick struck the post and bounced back into play where inside-centre Steve Leach forced his way over for a try.
This time full-back Oscar Heath became Bees’ third player to try his luck with the boot and he duly held his nerve.