The Computer Misuse Act 1990 contained, until 1 October 2008, its own limitation:
- Proceedings for offences under section 1
(1) A magistrates' court shall have jurisdiction to try an offence under section 1 above if—
(a) the accused was within its commission area at the time when he did the act which caused the computer to perform the function; or
(b) any computer containing any program or data to which the accused secured or intended to secure unauthorised access by doing that act was in its commission area at that time.
(2) Subject to subsection (3) below, proceedings for an offence under section 1 above may be brought within a period of six months from the date on which evidence sufficient in the opinion of the prosecutor to warrant the proceedings came to his knowledge.
(3) No such proceedings shall be brought by virtue of this section more than three years after the commission of the offence.
That section was repealed in its entirety on 1 October 2008.
Legislation is not generally retrospective, so it may have continued to limit the prosecution of offences committed prior to 1 October 2008 (which would have expired on 30 September 2011). This could have meant that it was possible to try only those offences committed between October 2008 and when the series was discovered.
Given that the last offence occurred "around six years ago" in 2010, it is possible that at least some of the series — those offences more than three years old — would have been out of time.
However, there doesn't appear to be any saving or transitional provision, so it's more likely that the abolition of the limitation actually made it possible to prosecute all offences committed after 30 September 2005, regardless of when they came to light or reached court.