A little while ago I posted about an MDPE weeping connection - thanks for responses.
Having prepared for destroyed olive, no insert or whatever, opened it up and found it was what it initially seemed to be - not done up properly to begin with and a bit of dirt/scale/slight scoring allowing the tiniest moistness. So I wrapped the olive neatly with some PTFE tape, tightened it up properly, and it is nice and sound.
For the first time, I used gas PTFE tape. Lovely and decent thickness, not flying away with static, easy to wrap neatly. Now I am wondering why they bother making non-gas PTFE. Is there any good reason? Or is it simply a cheaper and crappier product without other merit? (Not that Toolstation's finest was expensive!)