How long do outstanding warrants last?

I'm confused slightly. if warrants dont expire until your in custody no matter how old the warrant may be, how is it that i failed to appear in court after being charged with burglary 15 yrs ago, recently i went to see a solicitor 2 get this sorted out who then phoned the local courthouse 2 find out if i had anything outstanding. the lady at the courthouse checked the system for the whole of merseyside courts but nothing was on their system. how can this be if once a warrant is out there it out there, the solicitor i saw called the court house while i was present and also told me to 4get about it. huh? even tho the court have nothing on record would this be the case with the police national computer if my name was checked, do the court hold records of every outstanding warrant an do they search the pnc when searching for a warrant or are court and pnc systems unlinked