National Savings Products
The least risky of investment options are those offered by National Savings, which raises money on behalf of the UK Government.
While investment returns are not spectacular and some involve tying your money up for long periods of time they are nevertheless stable and in some cases can be paid tax free or paid without deduction of tax (although taxable), which is beneficial if you are a non taxpayer.
They include National Savings Bank accounts and various forms of savings and Income Bonds. These savings and investment products are backed by H.M. Treasury, which makes them the most secure cash products available in the UK.