I was the Fleet Support Engineer for HSBC on the 365 fleet for 8 years, supporting operation and maintenance of the fleet at Ramsgate and Hornsey, and was on the project team for the migration of the LSER units to WAGN.
All DC current collection equipment (shoe beams, cables, arc shields, fuse boxes etc) were removed during conversion at Doncaster works. One set were retained by Bombardier for possible pattern use at some point in the future but they were lost at Crewe works during the closure. The rest went in the skip. This was done as it was recognised at the time that the odds of 365's ever going back to DC operation were extremely long.
However, there are more significant issues with returning 365's to DC operation than just the missing current collection equipment. Just before the 16 units left Ramsgate it was found that the High Speed Circuit Breaker operation timings were out of spec and non-compliant with safety case requirements. Believed to be an age related issue, it was not closed out before the units left DC land and would prevent their return to DC operation.
There's also the small matter of many of the units having had their 50Hz monitors (known as Ansaldo's) removed and used on GEC traction equipped 465's. Unless something has changed since my last involvement then these are obsolete and no longer available, so that poses problems in its own right.
There is no "wiring loom" missing.
Operationally, 365's are not compatible with 465's except for recovery purposes. Auto couplers are wired slightly differently so train lines don't match and require the coupler switch be put in the "other" position, which means that some key train functions for normal operation don't work. But the bigger problem is that 365's are geared differently to 465's; 365's achieve a higher top speed by being higher geared, when compared to 465's, which means they don't accelerate as fast. If I remember correctly, 365's average 0.88ms2 and 465's average 1ms2. So coupling them together causes all kinds of issues.
Southeastern don't want 365's. Why would they want a small sub fleet that's not operationally compatible with any other stock they've got and that would require a whole new maintenance and material provision?
Now that's a response I like, full of the nitty gritty detail! Just one query from me - If the 365's were not compliant in regards to HSCB timings, would that also be a problem for the 465's(at the time)? I guess I'm really wondering if the 365 traction system operating in DC was ever the same as the 465 traction system (wiring/spec/design) notwithstanding the obvious additional hardware required for AC operation not being present on 465's