If there was a person or entity in charge of the liquidation you might start by contacting the person or entity. (If it was a formal liquidation then there ought to be such a person or entity, someone who exercised a degree of oversight or control of the liquidation of assets.)
If the authoritative emails for the domain are "attached" to the domain then I'm guessing that you have no email contact info. A work around might be to check Archive.org for any other details about personnel - who MAY be of some assistance. I've resorted to snail-mail and FedEx, as methods of making contact, from time to time. FedEx envelopes tend to grab people's attention and lend weight to the effort to make contact. Not cheap but, case by case, a sound investment of money.
Last resort is to pursue all available "drop catching" or auction channels for co.uk domain names. You might also reach out directly to the domain's registrar to make further inquiries.
Sometimes situations such as this are "money talks, talk walks" situations, ones where an opening line that includes disclosure of a willingness to pay (for the domain, for assistance, etc) can advance your effort to acquire the domain.
Have you actually checked that it is owned by the company?
I know of one national charity where a tech savvy committee member set up one of these new fangled interweb thingies for them when they first came out. When they wanted to get the management of the site in house it turned out that he had paid for everything on his credit card and it was all in his name.
... it turned out that he had paid for everything on his credit card and it was all in his name.
I've seen this many times, and in most instances, it's never been a problem: It's usually just a misunderstanding when it was orginally registered many years back. It's only when someone unscrupulous decides they can hold someone to ransom. In the one instance i've had this happen, it turned out that the unscrupulous person was on thin ice and should not have registered in their own name. Instead of thinking they would make a fast buck they ended having to hand over the domain. It did take some time, and it could have been costly, but all was well.