Number twenty.

I'm ≥99% certain I'll not "get" them all, but I'll keep my eyes open when downtown.
It just occurred to me that anybody under 40 was born in the era of Sillymoney. When we went "centimal" and called it "decimal".
The victorians tried, with a coin labelled "One Florin, one tenth of a pound"
There you go.
If I live 'till I die I shall maintain it would have been just as easy to have
10 Pence = 1 Florin
10 Florins = 1 pound.
I shall climb down from my stallion and translate 6/11
Six shillings & 11 pence (at 12 pence to the shilling)
A direct conversion to modern money would be 35P (to the NEAREST whole penny)
We married in 1972 and I was making around £10 per week
Dad Married in 1941 and as recently
as since "we" two were born was making £5 per week
Mam was born in 1905 and told us that her Dad set up house on a reasonably good wage of, brace yourself again 18/6 (18 shillings & 6 Pence)
SO - 6/11d was a goodly chunk of one week's wages and you'd probably have to save up for it.
I've just nipped off to check:- One source puts 1914 £1 = £100 "Today".
Which makes 6/11 (Call it 7/- {As 7 shillings was depicted}) would be, very approximately, £30-35.