The offence is prosecuted out of time
Minor offences (not an indictable offence) must be brought within 6 months from the date the offence was committed.
Offences include traffic offences, prostitution, shop-lifting, possession of class-b and misdemeanors
The conviction is discovered when commercial bailiffs turn up in ambush demanding money.
You can overturn the conviction by making a Section 14 Statutory Declaration, or approach the Parliamentary Ombudsman with a complaint about a breach of Section 127 of the Magistrates' Courts Act 1980.
The Law:
Section 127 of the Magistrates’ Courts Act 1980 states:
Limitation of time.
(1)Except as otherwise expressly provided by any enactment and subject to subsection (2) below, a magistrates’ court shall not try an information or hear a complaint unless the information was laid, or the complaint made, within 6 months from the time when the offence was committed, or the matter of complaint arose.
(2)Nothing in—
(1)Except as otherwise expressly provided by any enactment and subject to subsection (2) below, a magistrates’ court shall not try an information or hear a complaint unless the information was laid, or the complaint made, within 6 months from the time when the offence was committed, or the matter of complaint arose.
(2)Nothing in—
(a)subsection (1) above; or
(b)subject to subsection (4) below, any other enactment (however framed or worded) which, as regards any offence to which it applies, would but for this section impose a time-limit on the power of a magistrates’ court to try an information summarily or impose a limitation on the time for taking summary proceedings,
shall apply in relation to any indictable offence.
(3)Without prejudice to the generality of paragraph (b) of subsection (2) above, that paragraph includes enactments which impose a time-limit that applies only in certain circumstances (for example, where the proceedings are not instituted by or with the consent of the Director of Public Prosecutions or some other specified authority).
(4)Where, as regards any indictable offence, there is imposed by any enactment (however framed or worded, and whether falling within subsection (2) (b) above or not) a limitation on the time for taking proceedings on indictment for that offence no summary proceedings for that offence shall be taken after the latest time for taking proceedings on indictment.