Mr. Feargal Ó Brolcháin:

The profit will accrue on redemption. The bonds might be bought on the secondary markets at a lower price than the price at which they issued but they are redeemed at the full price. Once they are redeemed the difference is the profit. The value at purchase would be known. They mature in the early years so there is a lot less maturing in the later years. Therefore because there is less maturing the amount of profit reduces accordingly. I do not know what the individual rate on these is but this is the calculation that was agreed and fixed at a point in time.