I'm not a lawyer, but IIRC, legal action will force him to declare OPLtd bankrupt (if he doesn't finish cleaning up), which will not harm Craig personally. The bankruptcy, however, will prevent him from setting up more companies, at least for a few years, which should stop him from doing this to more people.
I just took a quick look at this place which I found via Google:
http://www.companieshouse.gov.uk/about/gbhtml/gpo8.shtml
And also, to verify the process is same for limited companies:
https://www.gov.uk/protecting-company-from-compulsory-liquidation
Things look very familiar, actually. Stuff I've heard from local friends and acquintances already... the UK differences are probably in the details which I don't know about, because I've never been involved in proceedings like this personally. This is definitely not rocket science, but there are pitfalls in this case, biggest one of which is clearly the one I've mentioned before: Scattered claimants.
You'll want to read chapters 5 and 6 of the first link.
Pay special attention to the difference between liquidators
responsibilities when talking about voluntary and compulsory liquidation:
Chapter 5, whole text:
"The liquidator is appointed to wind up the company's affairs. The liquidator does this by calling in all the company's assets and distributing them to its creditors. If anything is left over, the liquidator distributes it among the members of the company."
Chapter 6, just the first paragraph:
"The Official Receiver has a duty to investigate the company's affairs and the causes of its failure."
--> You can read this as "crap really starts to hit the fan here".
Also, for the people who do not want to bother with "Fancy Text " (i.e. most people ;-) this has been put in plain English in the second link:
"You can be banned from being a director for 2 to 15 years or prosecuted if the liquidator decides your conduct was unfit."
So, do not automatically think this would not harm Craig personally because the company is "Limited". It could.
One addition, I got interrupted and lost my thoughts for a minute:
Do note that compulsory liquidation is not neccessarily easy to "start", much less "enforce" at all!
This is not only because of the paperwork, costs, etc., but because the whole idea of systems like these is that you
first try to settle between the company and creditor without court orders etc.
then the company can still act in a panic and try to settle with the creditor when papers have been filed (i.e. the paperwork is considered as a "threat" more than a decisive course of action)
and only if both of these steps fail does your company end up in compulsory liquidation.
So it is a... whatcha call it... "graded" thing?
Like I have already pointed out earlier, Craig can probably avoid the heavy stuff by simply settling when things get too hot with a single creditor, because the sums involved are so very small.