S198 election on overseas property?

I am aware that a property investor investing in overseas commercial property can claim capital allowances on the same basis that they can on UK property.  Likewise if there is a surplus of allowances, these can (currently) be offset (without a cap) against general income – S121 ITA 2007.

OK so far so good. 

My question is that on a future sale what happens?  Do the allowances reverse or can the taxpayer make use of S198 CAA 2001 provisions to sell the asset for an agreed tax WDV / £1 even though the purchaser could very well be a non-UK taxpayer.  Is there anything to stop a 198 election from being effective? I know there is a requirement under S201(3)(f) CAA2001 to have tax district and ref numbers for the persons making the election but there is actually no stipulation this has to be UK references??!

Any help would be much appreciated.