Boxtops may be right about companies limited by guarantee but they aren't at all common for commercial businesses.
Wikipedia has this to say.
http://en.wikipedia.o..._limited_by_guarantee
Directors of a limited company do not have a personal liability to the debts of a business unless a loan has been taken out and a director has personally guaranteed the loan - hardly a situation I can think of applying to an HMRC liability.
Shareholders of course have a liability to the limit of their shareholding stake in the business (and I assume that this business has a director who is also a shareholder).
Strikes me that the HMRC people are proposing insolvency proceedings against the COMPANY but not the individual.
This can hardly be a surprise to the directors; corporation tax liability is never (normally) due until 9 months after the end of the relevant tax year of the business.