This is like my worst nightmare..although I am unfortunately one of those 'naive' people who wouldn't know what to do if this happened to them.
All I know is that the quicker you are in the public domain with your brand, the more established and known you are the more likely that you can legitimately claim rights to owning the concept. This is in reference to the 'passing off' argument.
Many times I'm given an NDA (when I was publishing games) by teachers who were too scared to share their ideas. But I realised that it's actually better protected once you get the idea worked on and 'out there'. The more work you put into it..i.e writing, designing whatever time value you add the more original and the less danger you have of someone copying.
Officially I always register my trademarks with the Intellectual Property Office in the areas that I plan on publishing i.e if you search 'Elemons' and 'Top Careers' they show the areas that no one else can use these terms in. This is a valuable property to me and I have already sold one brand to someone else because they knew that they wanted to use it globally but couldn't use it whilst I owned the trademark to it. Respectfully he asked if he could buy it and I, coincidentally, was selling it anyway a few weeks before they contacted me from Hong Kong. Look up 'Loop'...the guy just launched a completely unrelated brand to mine but he is now launching it on Kickstarter.
I highly recommend the investment of about £300 in trademarking your brand officially with the IPO. If you want support with your IP and further advice go to the British Library IP Centre
who offer so much advice and free workshops. They have advisors you can call who specialise in IP. It's all there for free. Valuing our work and copyright at the start will minimise or at best help towards defending it should the worse case scenario take place. Although this issue with the BBC is troubling indeed.