James
The current requirement is 30 years but is likely to rise to 35 if the current planned changes to pensions are implemented, also it is not the number of years that you have worked but the number of years that you have paid or been credited NICs, many of those on low pay often do not receive NICs at all, the only way to know for certain is to request a statement from HMRC.
In principle there is no point acquiring further NICs once you have met the then current requirement, but if the requirement is changed again, then you could still lose out. The changes will introduce a minimum number of NICs in order to receive any pension and not having the required number will result in a reduced pension.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
