Plaque

The photo showing the 1941 destruction is from Alamy. That tower to the right of the photo is one of the pair at Cannon Street Station, on the river frontage. So the wall with the plaque would have faced onto Upper Thames Street.

The later photo, dated 1966, is from Wikipedia.

An 1895 map shows "site of All Hallows the Less church" and also, with just a pub separating them, "All Hallows the Great and Less Church (remains of)".  That title makes sense when you know that when The Less was lost to the fire that parish was united with The Great.