A draft is not as good as cash and the banks are especially wary of them these days due to the sheer volume of counterfeit drafts out there. There is also no speedy clearing system between UK and Irish banks, hence UB will have to send the draft to the UK, wait to be told by the UK bank that it is cleared and then wait for the funds to be exchanged before they can say it is cleared at their end. That should not take 6 weeks, 2 weeks should be sufficient. However UB are dependent on the UK bank acting in an efficient manner, some are better then others in that regard