Well here is a start http://www.naturalengland.org.uk/publicati...ife/WML-A05.pdf
Clearly actually 'taking' any otters would be a bit drastic and I don't think anyone would support it. You may get permission to relocate somehow. However I think that it's unlikely they would grant a licence, certainly not straight off, and will push back on your mate to do more to exclude them.
Criteria are:
preventing serious damage to livestock, food for livestock, crops, vegetables, fruit, growing timber, or any other form of property or to fisheries,
preventing the spread of disease,
preservi