Suppose you expect to receive £1000 (moninal income) in one year from now. Just to get the setting right, we assume 'now' is year 0 and 'one year from now' is year 1. You expect the inflation rate to be 2% in year 1. Then your real income in year 1 is
Now suppose you expect to receive £980.39 in year 1 as above. And you know that nominal interest rate is 5% or in real terms appr. 3%(=5%-2%). Then, the present value of your real income discounted at the real interest rate of 3% is
The first demonstrates the calcluation of real income to be received in year 1. The second example shows the calcluation of present value of a future (real) cash flow using real interest rate. So, it depends on what (i.e. inflation rate or interest rate) is used in calcluating the discount factor.
If your £x is a real cash flow in year 1, then you do not need to discount it. Hope this helps.