Spot the difference street signs 2

What interests me about these signs is that although they appear to date from the same time there are subtle differences. They are situated opposite each other at the junction with Bayswater Rd.
Why the colon after the leading to... on the upper sign? Why have the postcode twice on the lower one (which also appears to use a narrower font)?
Also, on this pair, both streets are given the same prominence whereas in the Orme Court sign (previous pic) the leading to... is in a smaller font (which is generally the case I seem to recall).