If company is no longer in existence you can apply to the court to have any order struck out on the basis there is no legal entity to enforce it. However I would still reply to the HMRC on the basis it has been requested until such times as a court deems otherwise. If this is a limited company it should be a fairly open and shut matter to have it struck out. In terms of evidence it will depend on what you have by way of evidence I would recommend just submitting any document you have in relation to the matter even if what you have is not eventually taken as evidence it is still advisable to summit it.
I shall provide you with a helpful link that will assist you in finding a solicitor/representative near your local area. This will provide you with someone nearby your area who can assist you if required.
I hope this information proved helpful. You will find a local solicitor who deals with these matters on the law society webpage which is as follows;
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