As BladeRuner919 said, the third brake light may well be the culprit. I never had much water in the boot but the bulbs and their holders were rusty, however the aerial base and third brake light seals are old and also looked perished so I replaced them. A new third brake light seal is round or oval in section so pushing it back into position in the boot lid is a bitch to say the least, otherwise as it's been said, the whole lot just pops out again! RockyDave and I (use two of you) found a smear of silicone grease just helped locate the clips. Interestingly the old seal that came out was more flatter, but I assume that was down to nearly 20 years of high compression. I know some have been tempted to use a silicone sealant and mask the problem, but I'd rather have it as it was when new, but be prepared for some 'F'ing and blinding!