Unless the caravan is producing power no need for bi directional,double pole is usually a good idea 

and anything using a EHU shouldn't be exporting power anyway ... given they're connected via plugs that have the pins exposed when disconnected (automatic shutdown on grid loss isn't quite quick/reliable enough to prevent shocks).

Given that most caravans use the mains to re-charge the leisure battery (often the best part of 100Ah) I might be tempted to wonder if a B-type might be sensible to guard against faults between the a.c. and d.c. systems...

  - Andy.

Could it be feasible that in the future that caravans static or mobile would have PV on the roof?  What about motor homes?

It's normal to have solar to recharge the 12V battery.  But how many motorhomes would have a grid-tied inverter onboard?

hopefully none with a plug and socket hook up.... (!) the ability to generate and have live pins end of the lead is not a good idea.

Static caravans with permanent wiring might well however.

I suspect the better  holiday tourer may have an inverter, but not driving the same sockets as the shore power directly

Mike.

Some touring caravans, both motorised types and trailers have a UPS of several KW capacity. this supplies the same sockets with either mains power from a shore supply, or with an inverted supply from a battery bank. Charging of the battery is automatic from the shore supply, and sometimes also from the vehicle engine. Such systems are safe and can not produce a dangerous voltage on the exposed pins of  the plug.

but if they don't export, then there is no need for a bidirectional breaker.
Mike.

Agree.

What about burnt out neutrals,  could Bi directional and Dual Pole help in that situation?

RCDs for caravan sockets should be double pole anyway (as with any isolation device on TT systems). Residual devices of any kind generally won't detect neutral problems, as there's no corresponding residual (or leakage or earth fault) current to detect. Bi-directional ones aren't any different from unidirectional ones in that respect.

   - Andy.