You gotta admit that - even though they're pretending to be a couple - they do a bloody good job!
With all the bickering, I'd have trouble not believing them. This episode, of course, features the argument from last Tuesday, which is not only super-old-married-couple, but features Purdey reiterating Gambit's argument about no man ever up and leaving a woman: "Not if he really cared about her."
rsf thinks Gambit actually kissed her in that scene. If he did, this fic bit just sums it up:
It was probably the most chaste stolen kiss in the history of stolen kisses. Just a brush of his lips against hers, really, that didn't last long enough for her to be able to decide whether to encourage him or step on his foot. In fact, by the time she realized that he actually had kissed her he'd already gone back to watching the Russian agent in the swan boat.
Purdey turned her face away, just to prove she hadn't been affected, but she let her head rest against his shoulder. They did have to "make it look good" after all, and with Gambit's arm holding her so close there weren't that many options.
Besides, it was a warm shoulder, a broad, well-muscled shoulder, a comfortable shoulder – and it was her own fault she'd encouraged Gambit by using it as a shield in the first place. There were more options than the "distracted lovers" cover – especially when you were standing on a bridge over open water – but it had seemed so natural to step towards him and to wrap her arms around him that she had just done it, and now, somehow, she was going to have to live with the consequences.