spiregrain
So my findings were: - The on-street paint is in a poor state of repair.   I think it might not be easy to tell that it says "Play Street" if you didn't already know.  This applies to both of the marks.

There are two hinged Newham street signs at the west side of the street at the North and South corners.   I assume these can be opened up when the play street is in effect.   There is no signage on the neighbouring streets.