65+ Guaranteed Growth Bonds are provided by National Savings and Investments (NS&I) and you can secure them for a fixed term of 1 or 3 years. In these times of savings low interest, these may be attractive options for a pensioner if you want a fixed and guaranteed rate of interest. You can invest anything from £500 up to £10,000, but you have to be aged 65 to invest.
But remember that they will not provide you with an income as the interest earned is added to the original sum invested and only access it at the end of the term.
Also remember that you can invest in both terms. You can find out more here