I have a sneaky feeling you're not going to approve. I may have told a little white lie, I didn't notice the drain had been stripped when I did the oil change. It was quite a while after, when I looked under the car and noticed a small weep. OK, I dare say I may have been lucky and dodged a bullet there so I put my hands up. My bad.
In either case the plug was still tight with no play and I still had to unscrew it with the rachet to get it out and check, so it's not nearly bad enough to be sliding or wiggling. But it is partially stripped. I'm confident it's not my handywork as I was so super paranoid about stripping it in the first place that I just tightened the plug up to the washer, then gave it a slight nip with the rachet.
I'd been of the thinking of changing the oil frequently. Lots of theories on whether it be every 5k, 10k or more. I decided to go 5k. It's an old car i bought as a runaround for less than 2 grand and has a high mileage. I don't use it for work, just social excursions. So from that, next oil change is due in roughly 1500 miles. I'll admit I feel 5k is excessive, and it's £60 odd a pop to do a change, so I'll be increasing the interval for the next.
Anyway, short term fix was the ptfe tape and copper washer on the plug. It's tight on with no play but not over tightened. I can't move it by hand and the weep has stopped. I check it very regularly. (As well as keeping a close eye on the rear view mirror for the trail should it decide to go).
Long term is I'm re-threading it a size up from the current plug. I've already got the kit. And the method is demonstrated in one of the vids RoyC posted. As I see it, if I make a complete hash of it it's a new sump regardless and my go-to garage is a few minutes away. If I don't I potentially save some cash. If it starts weeping again it'll be quiksteel and I'll be doing subsequent changes through the dipstick.