To add a real punch, Luke added lime zest and juice to both his gingernut biscuits and his lime buttercream filling.  He had practised hard to make sure that the lime came through immediately, followed by the kick of ginger.

Judging

Paul Hollywood: "I think they look great. They look like a proper gingernut."

Prue Leith: "Mmm, the ginger is lovely. Just right."

Paul Hollywood: "The lime, however, it just isn't there."

Prue Leith: "Yes, it does need a bit more lime. Nice, though."