TWCLAM

Thank you for this. Was something I was going to look into but the link saved me the time looking.

Regarding the "your not a transit pax" whilst I agree and the BA flights are positioning ones made at the same time albeit separately I was, maybe wrongly as it turns out?, under the impression that both BA & AY being OW carriers there would be some way to link the bookings as I thought that was one of the 'things' that alliance partners did. BA said they couldn't and well AY's live chat CS is a lottery of either utter incompetence or passable basic knowledge from my experiences with them.

As someone who's never done this, preferring instead to always go point-point, the help and advice has been immensely helpful in furthering my knowledge so hat tip to you all.
I will live in hope that by the back end of October and it being outside of school holidays that some semblance of normality will have returned to AMS and the 4 hour rule will be done with and out the door queues/ hold zones will have become a thing of the past but now at least I have a better understanding of things thanks to you lovely lot.
Lastly on the "are you sure on your AMS-HEL timings" you were quite right. I'd done a cursory glance and quoted the HEL arrival time with the departure from AMS indeed being at 17:30