I saw this one and thought it must have been from a Halloween party, and that Mother just needed the broomstick before heading out for the night. Unfortunately it turns out that it’s Hospital Ball from early 1965 – she worked there before The Brother arrived.
On the subject of Halloween, SWMBO
a) Persuaded her grandfather to make a proper broomstick for Mother.
b) rang Mother on the 31st October hoping to catch her before she went out for the night. Amazingly, Mother still talks to her!