Step 1:
Calculate the Customs Duty:
3.7%of £140 = £5.18
However Customs Duty is waived if it comes to less than £9 (or if the value of the goods is less than £135), so you get away with that bit.
Step 2:
Calculate the VAT. It's charged on the value of the goods AND on the carriage costs (although I've known that element to be overlooked sometimes). If there had been any Customs Duty there would also have been VAT on that as well. (Yes, you have to pay tax on a tax!):
20% of £175 = £35
Step 3:
Add on an £8 customs examination fee:
£0 + £35 + £8 = £43 to pay.