Anyone know if there are any laws governing whether you can leave a trailer unattended by the roadside?

There's one been sat across the road from me for a few days taking up 2 parking spaces which is starting to piss me off as its not connected to a car or doesn't really seem to be serving a purpose...

Its got a reg plate on it which I've just checked but the RAC website doesn't have a any details for that reg

to top it all off the bloke a few doors down from me has just caught the front of his car on it and made a bit of a mess