Haven't used Worldpay myself but checked out the Worldpay site.
This is what they say:
"Bogus emails: In the last few hours some customers have received at least one email from a 3rd party pretending to be WorldPay - some using the bogus address [email protected] / [email protected] and the name Dave Gollick - but other names and addresses may also be used. This email is not from WorldPay - we recommend you delete it and do not open any attachments it may contain."
No payment service i.e Paypal or Worldpay in this instance, will ever ask you to disclose your log on name/pin in an email. Your always best to log into either Paypal or world pay by their web address, rather than clicking on a link from an email that could be a bogus email and would direct you to a bogus site.