On 8 July, 01:40, Basil Jet wrote:
It turns out that for Saturday and Sunday, the District Line is shut
from West Kensington to Ealing / Richmond, and the North London Line is
shut from Willesden to Richmond. Since these three services are the only
three serving the Chiswick Park / Gunnersbury area, I'm wondering if it
was necessary to shut all three at the same time, when no track or
structure is used by more than two.

I don't know about the NLL but I was told by somebody within LU that a
section of track on the District Line had to be replaced and so the
Piccadilly Line had to be closed for H&S reasons.