Notes to the consolidated financial statements

3 Significant accounting estimates

The key assumptions concerning the future and other key sources of estimation uncertainty at the balance sheet date that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are discussed below:

a) Defined benefit pension schemes

The determination of the Group’s obligations and expense for defined benefit pensions is dependent on the selection, by the Board of Directors, of assumptions used by the pension scheme actuary in calculating these amounts. The assumptions applied are described in note 26 and include, amongst others, the discount rate, the inflation rate, rates of increase in salaries and mortality rates. While the Directors consider that the assumptions are appropriate, significant differences in the actual experience or significant changes in assumptions may materially affect the amount of the Group’s future pension obligations, actuarial gains and losses included in the Consolidated statement of comprehensive income in future years and the future staff costs. The carrying amount of retirement benefit obligations at 31 March 2010 was £13,082,000 (2009 – £8,764,000).