The generators fitted to the Class 27/2 were indeed very unreliable, prone to catch fire and rather under powered as mentioned above. A clue lies in the fact that the Mk2zs used on the service were dual-heat, the Class 27/1 used at the other end of the formation retained its steam-heat boiler, as the ETH generators were so unreliable that steam heat had to be retained as a back up. Another unusual feature of the Mk2zs was the braking system, at first look it seems like a usual twin-pipe air system but in addition to disc brakes being fitted, Girling WSP equipment and a unique two-stage system was employed. At speeds of over 60 mph the brake cylinder pressure was automatically increased to provide a consistent retardation rate from 90 mph to a stand. Full service braking was the norm with both the Class 27 push-pull sets and the later Class 47/7 sets. The frequency was half-hourly off-peak Mon-Sat in those days with services alternating between calling at Haymarket only or Falkirk High and Haymarket. This service and calling pattern continued but bizarrely the journey times were actually increased with the Class 47/7s, despite their 100 mph top speed. Services took 37 mins to Haymarket (41 to Waverley) non-stop and 39 mins to Haymarket (43 to Waverley) calling additionally at Falkirk High. The journey times for the Class 47/7 services were extended by 6 mins in both directions. At a mere 41 mins for a Haymarket only service from GLQ to Waverley (averaging an impressive 74.6 mph non-stop GLQ to Haymarket), the service was very definitely quicker than what the new Class 385s will achieve, albeit with a better service frequency and more stops. Also, the formation was six Mk2s, Class 27/1-TSO-TSO-TSO-TSO-FK-BSO-Class 27/2. The BSO was marshalled at the GLQ end and in later years with the van against the FK rather than the loco.