External training is appropriate where it is required to: 
 
• acquire highly specialised clinical skills that are unavailable within the training network, at a centre of recognised excellence; 
• participate in or promote qualified scientific projects at a centre of excellence in the relevant field; 
• combine the acquisition of advanced clinical skills with participation in a scientific project. 
 
The School Director must state which reason supports the request and attach a brief report explaining the proposal, its educational or scientific aims and the excellence of the host centre.