This has been placed by the 1st/7th Whitley Bay Sea scouts.
During the early part of the 2nd World War it was very common for the Luftwafffe to come visiting Tyneside and leave some unwelcome presents for the shipyards and docks on the river. They wouldn't get away unscathered as the RAF would go up and say hello. Commonly the German bombers would run to the sea before reaching their target and jetison their bombs on coastal towns.
On the night of the 16th April 1941, two parachute mines hit Ocean View in Whitley Bay resulting in 15 deaths, 14 on Ocean View and 1 on Mason Avenue. Their names are included in the Civilian War Dead Roll of Honour in Westminster Abbey.
You can still see the result of this tragic incident on Mason Avenue. If looking from the top (south) end of the street, the line of houses on the right were damaged beyond repair and rebuilt after the war. You can pick out certain architectural features that differ from those on the left built in 1927. For example the bay windows and the stone mullions. Need to bring a pen.