BBC filming ban?

I’ve been having a discussion about this with my friend tonight, and I figured it couldn’t hurt to ask here.

I can remember taking a tour of a castle in South Wales as a child, and having a tour guide taking us through the rooms. He mentioned that the BBC had filmed several shows there, but that they had to ban them after they painted an internal wall without permission.

I have been trying all evening to find more information on this, but to no avail. I initially thought it had something to do with Doctor Who, but my research hasn’t turned anything up confirming this.

What I want to know is am I imagining this? If I’m not, does anyone have any information about this little anecdote? And why, if it’s true, why was there no trace of it on the internet?

I know this may be a weird topic, but it’s been playing on my mind all day.

Roughly what year are we talking here? "As a child" might only go back as far as the start of New Who in 2005...

I reckon maybe around 2009/2010?

This sounds like the kind of contract dispute that is best kept quiet on both sides and therefore it isn't surprising that there is nothing on the internet about it. This kind of thing becoming public has the potential to cause issues for both sides whereas if it is kept private things can move on with little drama with the BBC agreeing to film in other locations (and quite possibly paying the cost of reinstating the previous colour on the walls) while the management of the building don't risk coming across as awkward or as though they had failed to read the contract properly.