You are welcome to pay with Pounds Sterling (£), Euros (€) or US Dollars, using the exchange rates on your invoice. The rates on your invoice will always be taken from xe.com on that particular day.
Prices on my shell list are based on the Euro (€). The list gives the approximate equivalent in Sterling and US$, but these are merely guides. Irrespective of any exchange rate fluctuations, the shells are invoiced in Euros.