1930s Wages and bonus

[oakville]

I came across a job offer my Dad received from Bristol Aeroplane Company in 1936.
The terms spelled out were "Rate of 47/- +12/- + bonus per 47 hour week"
The bonus was a fluctuating figure and depended on output but recent earnings stated "have been between 30% and 35% on flat rate".
What was the 12 shillings?. A shift premium perhaps. What was Dad's estimated earnings?
I don't want to think he was holding out on us.

[Ethel]

Your dad's average was 74/4 - 3 pounds 14s 4d.

In 2005 that was equivalent to 168.23

http://www.measuringworth.com/calculators/ppow eruk/result.php?use%5B%5D=CPI&year_early=1936& pound71=&shilling71=74&pence71=4&amount=3.7166 66666666667&year_source=1936&year_result=2005

[oakville]

Thanks Ethel for the information however, I still don't understand what the rate of 47 shillings + 12 shillings means. What is the 12 shillings for?
47 shillings is an rate calculated on a 47 hours work week presumably, but why is 12 shillings (25% more) added.
Then there is a bonus 30% -35% added on top of this.
Any ideas?

[Ethel]

The bonus would have been output. If the company targets were achieved each week the bonus would be paid, in addition to the flat rate of 47/-.

The 12 /- could be a number of things - an enhanced pay for a supervisory role (foreman), or shift work or an additional responsibility or skill your dad had. Or even danger money if the work was in any way hazardous.