Hunt him down with a British infantry squad equipped with a marksman. The moment he shoot one in the squad you counterattack him with the markman, yeah you going to lose 1 to 3 men maybe. But you get the sniper down :3
Trap the sniper blob in with commandos. So when you charge your recon squad at the snipers, if he is good most likely he will run away uncloaked, baiting you into an MG42. In that case and at the right time, drop in some commandos, not directly on top of them, just on the path they are going to and instant retreat. Works 90% of the time if you master it
Just.. dont... play brits