J Lynch wrote:

The Gunnersbury - Richmond service referred to on the District Line
is presumably actually the Silverlink North Woolwich service?

LU say it's 2 trains at 20-minute intervals. I think it's likely that 2
District trains were stabled at Richmond overnight and are running a
shuttle service to and from Gunnersbury, under Network Rail signalling,
using ASLEF or rebel RMT drivers.
--
Richard J.
(to e-mail me, swap uk and yon in address)