State pension payments could rise to £935 a week from April next year, but over 500,000 pensioners will miss out on this boost. Under the triple lock, the state pension increases each year in line with either the rate of inflation in September, average earnings for May to July or 2.5 per cent; whichever is the highest. However this does not happen for those living overseas unless they are living in a country which has a reciprocal agreement with the UK. This means British pensioners living in countries including Canada, Australia and Thailand receive much smaller pensions than those living bac…