I realise it states in Wiki that the FIDF is entirely funded by the Falkland Islands Government, but I'm not 100% sure how accurate that is.
The Falklands Islands Government's own website states that the islands are self sufficient in all areas
except defence, which comes out of the UK defence budget.
http://www.falklands.gov.fk/Economy.html
(It is, of course, possible that the UK contribution refers to the British Armed Forces on the islands and the FIDF are classed separately from that).
Either way, I agree with HorseSoldier...whilst I follow the logic behind the decision, it strikes me as a little unusual that the FIDF would go with something other than the L85...jmho...