Jackie,
Just watched the CCTV film of your caravan being stolen and it made me feel sick inside. It's something we all dread.
When we're not using our caravan, it's stored on a secure site with swipe card entry and cameras cover the whole site. The owners house overlooks the storage site too. We put the hitchlock and wheel clamp on and the caravan alarm on.
Before a trip, the caravan is on our drive and the wheel clamp and hitch lock are put on immediately and stays on right up until we leave. When we're in and out loading it, we lock the door whenever we leave it and never leave the keys in the unlocked caravan while we go indoors. We've told all our close neighbours that nobody has permission to move our caravan off the drive (but tell them if someone DOES!) and to call the police immediately if they see anyone trying to take it away, even if challenged and they say something like they have permission to take it away for servicing. We also park an alarmed car (with detachable towball) across the front of the caravan, but as they say, a determined thief will take it and all you can do is make it as difficult and time consuming as you can for them. Scumbags!!
Just watched the video and I know 20 20 hindsight is a wonderful thing but may I make a suggestion that may frighten off the scumbags next time.
I also keep my van on my drive complete with wheel clamp, caravan alarm etc, and we all saw that this made little difference, however I connected my caravan to my house alarm.
Quite simply its a matter of wiring a 2 core cable via a switch (a light switch would do)to the panic button or panic button circuit of the alarm box, the reason for this is it is always armed even when the alarm is switched off.
The cable in my case went to a 2 pin water proof plug and the plug socket was attached under the caravan but obviously accessable. The socket pins were connected together.
So to take the van the thieves had to unplug the cable or cut the electric cable thus setting off the house alarm.
The circuit is low voltage so is perfectly safe.
The added light switch is to short out the cable when taking the van on holiday.
The cost was minimal yet gave extra security, of course if you have an alarm system that when triggered would phone you all the better.
Hope this all makes sense.