Basil Jet wrote on 21 May 2018 at 13:53 ...

Are they allowed to do that? I suspect it was put up by the "Friends Of
Lea Road".

Depends which version of Johnston font. If it's the original Johnston in its digital form, licensed by TfL exclusively to P22 Type Foundry, that's now a commercially available font.

If they've used New Johnston or Johnston 100, they have probably violated TfL's copyright. There are also a number of other fonts based on Johnston such as Granby and ITC Johnston which are presumably independent of TfL.

I'd need a high-res photo of the sign to decide which font it is.

--
Richard J.
(to email me, swap 'uk' and 'yon' in address)