Hello When watching the DVD I noticed the following. The sound of a PIS onboard the unpainted train Dave was driving at one point St James Park can be heard. And the all doors open on the unpainted D stock when opened by the driver, when was the button made redundant. Thanks.
The unrefurbished silver D78 stock had maintainer operated 'POGO' switches (Passenger Open / Guard's Open) switches. After conversion to one person operation the name still stuck! In the first few years the trains tended to be worked Operator Open in the summer, to help with ventilation and Passenger Open in winter. But as the ridership grew in the 80s it wasn't long before they were run Operator open all the time as I recall it. So Operator Open represents the majority of the time these trains ran.