I signed a contract with a builder for some rendering on the house. On reviewing the contract it refers to itself as "xyz" builders of such and such place. No reference to ltd. Checking on Companies House this company appears dissolved. Also the builder hasn't signed it. Then I checked VAT number and it was registered against a similar named company, xyz (town) ltd. Surely this is misrepresentation and invalidates the contract?
Clearly, a dissolved company cannot be a party to the contract.
The fact that the builder hasn't signed the document doesn't necessarily mean that the terms of the document aren't incorporated into your contract; but depending upon all the circumstances there could be an argument to that effect.
As to the contracting party: the trading name "xyz" could be a trading name of: (i) the builder as a sole trader; (ii) a ltd company (such as xyz (town) ltd); or (iii) some other entity. The VAT number would strongly suggest (ii).
Using a trading name isn't itself a misrepresentation, although there are a range of statutory rules about identifying contracting parties in contracts with consumers.