I used to be based in the North-West and used the Clansman a few times - the 1986 variant was probably the best Clansman service.
The set used for the 1986 "Mk3" Clansman was formed up of three half-sets.
Two half-sets were the Inverness portions, as discussed, formed:
NHA (110mph BG) + Mk3a FO + 5x Mk3a TSO
These worked the Inverness portions, and were always the "country end" of the train at Euston, and worked a two-day circuit, EUS-INV one day, INV-EUS the next.
The IS-based RMB, 1869, would work Inverness-Perth-Inverness, coupled to the "London end" of the train. Attaching the RMB to the down Clansman was done by the Perth-based 08 shunter when I last used this service, and there was no additional BG attached at Perth. I think the train engine performed the shunt to remove the RMB on the up working.
The other half-set was the Glasgow portion, formed:
3x Mk3a TSO + RFB + Mk3a/b FO + Mk3b BFO
This worked a one-day circuit EUS-GLC-EUS each day of operation.
The full rake was a 13 coach "monster" and probably one of the biggest day trains on the WCML at the time, if not the biggest (the PC-based Mk2 half-sets which worked the Glasgow/Edinburgh splitters usually being 11 or 12 coaches, usually variants of - 4xTSO+BFK+Buffet+BFK+4xTSO and the occasional BG).
The 1986 Clansman also deviated from the "Mk2 Clansman" variants because it was part of the main Euston-Glasgow 110mph services, therefore was routed via the Trent Valley and didn't serve Birmingham.
In terms of train operations, on the down, the full train ran to Carstairs, where it was split.
Then Inverness portion would be worked forward by the 87 which had brought the train from Euston, as far as Mossend, where a (usually IS-allocated) 47 would take over.
Back at Carstairs, another AC electric (whatever happened to be available at Carstairs) would attach to the front TSO of the Glasgow portion, and work it forward to Glasgow Central.
The 87 which had been released from the Inverness portion at Mossend would then work forward light engine to Glasgow Central, and then attach to the return Glasgow portion of up the Clansman to work it back to London.
The up Inverness portion, having shed the RMB (and occasional BG) at Perth, would be diesel worked through to Carstairs with no traction change happening, and would arrive in advance of the portion from Glasgow. The 47 would run round to be on the North end and then shunt the train clear of the platform, into the up siding used for attaching portions (so a bit like an Edinburgh portion, in that respect).
The portion ex-Glasgow would arrive in the platform with the 87 at the head. The 47 would then propel the Inverness portion onto the back of the Glasgow portion in the platform, before detatching, then the 87 would take the full consist back to Euston.
Hope people found this useful.
Mike