The other Parkway station was somewhere near Potters Bar for the M25.
Silver standard was definitely carried forward from BR to GNER, certainly up until 2002, but I dont know if NoL 373s had this.
The selective door operation that the NoL sets had was later altered. Initially, the doors on the outer two cars at each end were not released at stations. This was okay when the the leading power car and two coaches overran the platform, but at some platforms the leading two cars were in the platform. However, passengers had to walk through to/from the third car which was highly irritating when terminating at Kings Cross!
Switching out the rear two, front two, and front two and rear two together seemed to be the resolution.
There were times of the day when they weren't supposed to run on the Southern part of the ECML (south of Hitchin I think) as during the rush hours there wasn't enough power for them as well as all the WAGN suburban services. They were something like 16,000hp as opposed to about 6000hp for a class 91. I think there was a restriction via Hertford North due to power supply too.
Nice comfy trains.