The file also suggested that the fireman regularly used semaphore to signal to the fire boats.
That looks like a quite camp demonstration of second position in ballet to me. I am sure mummykins can whip me up a pair of quilted appliqué semaphore flags for the good ship Betty.
Anyway, here goes…
Can you tell what it is?!
betaiiifireboat 
Yup. Beta 3.. interestingly I didn’t realise that the numbers corresponded to the letters of the alphabet eg a=1, b=2 etc Obviously I didn’t concentrate enough when watching Dad’s Army!!!