I'd suspect they were the HC3's uniquely ordered by the UK powers the be to a wrong spec, then stuck in a hangar for 10 years debating what to do with them, before which they suffered extensive corrosion.
Only in a country as breathtakingly daft as this could such cluster f**k occur.
See
http://www.pprune.org/military-aircr...ook-hc-3s.html