I don't know the answer first hand for the Helicycle case, but my guess would be that if they approached the CAA to bring it into the UK, the CAA would have turned around and said:
"Fine, here's the regulations that you need to prove it meets, come back when you've done it in a way acceptable to us"
In addition the CAA will charge large sums of money to look over the approval, which I guess is not justifiable based on the UK market for such a machine.
Hope this helps.
CRAN
