2 - I also recently bought a Vulcan rear crew PEC with Pressure Jerkin fitting. No, the rear crew had the MSC, a huge block of metal called a Multi-Service Connector. Martin Baker took one look at it and said 'not on my seats' and designed the PEC. When swivel seats were fitted the connector became the SSC or swivel seat connector.
I have a Mk4 Pressure Jerkin - the Jerkin fitting seems to align quite well on Lightning, Bccaneer and Sea Vixen PEC's, but the Vulcan rear crew PEC seems a little long, as though the mask oxy hose would poke you in the chin! Was there a special Jerkin for the Vulcan rear crew? The jerkin was the same for all Vulcan crew. The connector may seem long but remember it was not used with the swivel seat.
What masks were suitable for flying with the pressure jerkins? A-13, M-Type or P/Q-Type? Would the Vulcan's have been operated with all mask types over the years in conjunction with Pressure Jerkins?
The M-series, a copy of an American mask iirc had a flat sealing strip, it didn't hold the pressure properly. The P/Q had an innovation by turning the flange inside. The M-series was mentioned but I dont know if it was used on Vulcans