National insurance record - pension

I appreciate that generalisations are probably not possible but I put this query out there just in case there is a simple answer. I understand that the current maximum state pension in £221.20 per week, which is about £958 per month. My wife has just claimed hers and it has been confirmed that this is what she will receive. We were with a close friend at the weekend who has just turned 65 and will be claiming her state pension next year. She showed us her HMRC account forecast was £1,005 per month (roughly), which is more than maximum. My wife had been contracted out for a few years in a company pension scheme and had to pay the shortfall in NI to receive her full pension. But this friend was similarly in a company pension scheme for a few years. We have lived abroad for a few years and not contributed NI. But this friend has similarly lived abroad and not contributed NI. But for longer! So what could be the reason for her increased forecast? We know with certainty that she has not made any additional contributions over and above normal PAYE NI.

Hi Jedcol,
Pension entitlement is calculated by DWP, based on the NI collected and recorded by HMRC.  
HMRC can tell you what you are obliged to pay and also what you can pay voluntarily, but I am afraid we cannot advise how the NICs you have paid will impact your pension entitlement, nor can we comment on the amount you will receive or even confirm if the maximum payable you have quoted is correct.
Your wife will need to speak to the future pension centre on  0800 731 0175  (8.00am to 6.00pm Monday to Friday) to establish if she can improve her entitlement
Thank you.