For people not yet retired the minimum is 10 years to get any pension at all. For a full pension you need 35 years. If you have between 10 and 35 years your pension is reduced by one thirty-fifth of the full amount for every year you are short of 35.
I agree with previous post, however there is also a reduction of State Pension if you have been in employment where you have been Contracted Out at any time. Just something to bear in mind as this has caused a lot of confusion where people have expected a full pension and ended up with less.