So far as voiding a conviction is concerned, a Statutory Declaration must be served upon the designated offer within 21 days of the defendant becoming aware of the proceedings - Part 37 of the Criminal Procedure Rules applies. The effect is that the hearingis treated as not having taken place: the conviction is therefore set aside but a further hearing may take place, the purpose being to ensure the defendant has the opportunity properly to defend himself. It doesn't bring proceedings to an end, it resuscitates them. The laying of the information is not voided. As a matter of public policy, a defendant cannot avoid proceedings by successfully ignoring them.
Section 127 imposes a six-month limitation period, but it says that a case may not be heard unless the information is laid within six months of the offence. If the information was laid in 1994 (presumably so, given the OP instructed solicitors to deal with it at that time) then there appears to be no prohibition on him being tried now.
By the way, schedule 3 of the Parliamentary Commissioner Act 1967 says that the commencement or conduct of criminal proceedings in any court in the United Kingdom is not subject to investigation by the Ombudsman.