I had to research a bit and put together some logic but it works for me
Used an if to determine if the value was plus or minus
For minus I took the value as a text string
removed this minus sign
times the value by 24
times the decimal value by the hourly rate
used -1 to make the answer a minus £ amount
For positive number done the normal.
Its not the tidiest of formulas, no doubt someone could tidy it up for me, but it works
Just proves the only thing excel cant do is give us a bit of imagination.