Just opposite Earlsfield Station in South-West London, two ghost signs are almost facing each other.
The first is extremely cryptic: only "S.P.O. &" remain visible. (The apparent tail turning the O into a Q is a trace of another sign, in darker paint, now illegible.) My first guess was that SPO stands for sub-post office, but a photograph of 1915 makes that unlikely. The full sign is visible (meaning it's close to a century old), and the wording is "SPO & Dining Rooms". The business underneath is A Martin Dining Rooms, with no postal services in sight. One mystery is solved, but another remains!
This sign does have a bonus feature, though. Above the ghost sign itself is a red-brick diamond, containing a stone inscribed 'Erected by J Doerr. H Boulter builder 1880.'
Diagonally across the road is another sign, equally intriguing. Only the left half of it remains - but there is no obvious reason why this part should have survived while the rest completely disappeared. One possibility is that a billboard or sign was placed onto the wall, covering part of the painting underneath.
What remains reads 'B J B... Pawn... Genera... Also at 2...'. We can guess that B J B... was a pawnbroker, and also engaged in general something-or-other, with two shops. Sadly, the full wording remains a mystery.