It is not uncommon for the unfortunate person on the end of the phone at FCL to find themselves put on the spot by a punter with an awkward point of air law. Its a bit like trekkies at conventions asking Bill Shatner why he didn't engage the warp drive in Episode 43 of Star Trek. Normally, like good politicians, they shrug it off and refer you to the legislation, rather than making a pronouncement that puts them in an awkward position. Sometimes though, you can catch some of the more junior ones out.
Fortunately the ANO is pretty clear on this. Without resorting to the FAA example for a moment we already know that the ANO renders valid any and all foreign-issued JAA licences. Most of these foreign-issued JAA PPLs will allow flight out of sight of the surface. These are validated without any additional restriction.
I very much doubt that your contact at the CAA would be prepared to put something into writing which implies that the CAA is curtailing the privileges of foreign-issued JAA licences. But it would be fun to trick them into it...
Charlie