Great to read this thread.
Our local station master (on the south coast) knew of my and my fathers interest in railways and alerted us to the trial runs being undertaken with passengers in the early 80s. He booked us on a day rtn trip Euston to Preston on the APT - maybe c1982? - which was a releif train to a normal service - a good example of local BR staff 'selling the product'!
I would have been aged about 13. Of course this missed the twisty section north of Preston - which I now regret missing - but as we assumed the trains would be rolled out to full service in due course, we viewed this as just a taster trip of what was to come. After arrival at Preston we pretty much got on the first train back to Euston, can't recall what that was but maybe an 86 and Mk2s - at that time they always seemed to retain Mk1 buffet / restaurant cars in WCML rakes I seem to recall,which seemed odd to me then.
Anyway
APT interior felt specious and modern to me (most of my rail travel was Mk1 EMUs and only the occasional HST on WR or ER), and I seem to recall thinking the buffet area was swish too. The pics above of course very much bring back the sense of it (I must go to Crewe to look). Note how most of the seats are table seats - as were HSTs/Mk3s before their late 80s interior refurb IIRC, much less cramped than a Pendolino seems to me, though the larger windows may help in that regard, and I was shorter then!
The large, and lowish (?) windows were great on the APT. Sound insulation was good (well, if a Mk1 is your benchmark that is probably bound to be the case...). The tartan upholstery was very fashionable at the time I seem to recall.
I have no recollection of power car noise. Speed, power and acceleration sticks in my mind. It all seemed very much the shape of things to come to me at the time.
I think I have a few bits of ephemera from the trip somewhere. Very glad our station master was kind enough to sort it all out for us. A kind chap who always had time for a chat.
My other recollection is of a spotting session at Euston when an APT was at a platform. The crew generously invited me and a few others hanging about at the end of the platform into the cab, which was a treat. It seemed very high tech and modern. I guess it did not leave on a run whilst I was in the vicinity or I might have had more of a sense of power car sounds. I suspect I have a few photos of that occasion, though film was a precious commodity for a 13-14 year old even in the 80s!
I probably didn't hang about after cabbing it, but would have headed over to Collectors Corner for a poke around, which was usually combined with a trip to Euston!
Fast forward 15 years to when I met my partner and I was impressed to find out her father worked at BR Research, including work that linked to the APT early testing at Old Dalby etc
The BTF film on the APT (Round Trip to Glasgow) which I think was never really released at the time, always brings back a sense of that trip I took when I see it.
As far as this 13 year old enthusiast and passenger was concerned, it was a great train and I salute all who worked against the odds to make it happen.