hat claim is bizzare. And btw, getting your company legal takes a month for it to get it into the legal system. So this claim could just be dismissed faster than they can argue it.
A year ago, I created a business license for my company, I changed the name of the entire network from CarlosX360 Network to CarlosX360 Co. Ltd. The license expired in July of 2010, and I still used the company's name, in october, I fully incorporated the company, but I still used the name - the name did not become fully legal until December. So, basically, iB just shot themselves in the foot by making this claim.
In the UK, the company is regarded as a legal entity from the date of incorporation, i.e it is liable for its actions.
Radon Systems Ltd underwent filing for registration on 22nd December 2003, but was registered on 23rd December 2010 as per the Companies House. From the 23rd December onwards, it became liable for its actions, regardless of it trading or not.
The UK doesn't have a business license as such, however, they do need licenses for multiple things. I believe that XenForo may need an ICO/DPF license, talking of which, they are super slow to issue such.