| Balance at 1 April 2011 | 2.1 | 151.0 | (0.6) | 0.5 | 0.2 | (0.6) | 169.8 | 322.4 |
| Total comprehensive income for the period | | | | | | | | |
| Profit for the period | — | — | — | — | — | — | 68.4 | 68.4 |
| Other comprehensive income | | | | | | | | |
| Foreign currency translation | | | | | | | | |
| differences for foreign operations | — | — | — | (0.5) | — | — | — | (0.5) |
| Cash flow hedges: | | | | | | | | |
| Fair value changes in the period | — | — | — | — | — | (0.9) | — | (0.9) |
| Transfers to inventory | — | — | — | — | — | 1.3 | — | 1.3 |
| Transfers to net profit: | | | | | | | | |
| Cost of sales | — | — | — | — | — | (0.2) | — | (0.2) |
| Income tax on other comprehensive income | — | — | — | — | — | (0.3) | — | (0.3) |
| Total other comprehensive income for the period net of tax | — | — | — | (0.5) | — | (0.1) | — | (0.6) |
| Total comprehensive income for the period | — | — | — | (0.5) | — | (0.1) | 68.4 | 67.8 |
| | | | | | | | |
| Transactions with owners | | | | | | | | |
| Share options exercised | — | — | 4.6 | — | — | — | (2.5) | 2.1 |
| Share-based payment transactions | — | — | — | — | — | — | 2.1 | 2.1 |
| Purchase of own shares | (0.1) | — | (18.0) | — | 0.1 | — | (44.7) | (62.7) |
| Income tax on share-based payment transactions | — | — | — | — | — | — | (0.4) | (0.4) |
| Dividends to equity holders | — | — | — | — | — | — | (44.2) | (44.2) |
| Total transactions with owners | (0.1) | — | (13.4) | — | 0.1 | — | (89.7) | (103.1) |
| Balance at 30 March 2012 | 2.0 | 151.0 | (14.0) | — | 0.3 | (0.7) | 148.5 | 287.1 |
| Total comprehensive income for the period | | | | | | | | |
| Profit for the period | — | — | — | — | — | — | 52.7 | 52.7 |
| Other comprehensive income | | | | | | | | |
| Cash flow hedges: | | | | | | | | |
| Fair value changes in the period | — | — | — | — | — | 2.8 | — | 2.8 |
| Transfers to inventory | — | — | — | — | — | (0.7) | — | (0.7) |
| Transfers to net profit: | | | | | | | | |
| Cost of sales | — | — | — | — | — | (0.1) | — | (0.1) |
| Income tax on other comprehensive income | — | — | — | — | — | (0.7) | — | (0.7) |
| Total other comprehensive income for the period net of tax | — | — | — | — | — | 1.3 | — | 1.3 |
| Total comprehensive income for the period | — | — | — | — | — | 1.3 | 52.7 | 54.0 |
| | | | | | | | |
| Transactions with owners | | | | | | | | |
| Share options exercised | — | — | 0.8 | — | — | — | — | 0.8 |
| Share-based payment transactions | — | — | — | — | — | — | 0.1 | 0.1 |
| Purchase of own shares | — | — | — | — | — | — | (0.9) | (0.9) |
| Income tax on share-based payment transactions | — | — | — | — | — | — | 0.3 | 0.3 |
| Dividends to equity holders | — | — | — | — | — | — | (42.7) | (42.7) |
| Total transactions with owners | — | — | 0.8 | — | — | — | (43.2) | (42.4) |
| Balance at 29 March 2013 | 2.0 | 151.0 | (13.2) | — | 0.3 | 0.6 | 158.0 | 298.7 |