At places such as Lewisham, the Central London "plough" system of
underground electrical pick-up gave way to the familiar "overhead"
system. At that point "the plough" was disconnected, and went off
into a siding; the overhead pick-up was hooked to the overhead
cable, and the tram continued its journey.
I only know this because my father-in-law told me - he used to
watch it in Lewisham High Street - but there must be film of such
an interesting changeover; I'd love to watch it for myself. Does
anyone have a link. When I Google "tram" and "plough" this film
comes up. Doesn't look too safe to me LOL:
https://www.youtube.com/watch?v=rTjRUT98lvE