v3.26.1
Financial instruments - Fair values and risk management - Maturity profile (Details) - EUR (€)
€ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 4,473.0 € 5,565.4 € 5,324.2
Cash Flow Hedges | Cross currency interest rate swap contract      
Disclosure of financial instruments by type of interest rate [line items]      
Gain (loss) on hedge ineffectiveness recognised in profit or loss 0.0    
Unsecured debt | Fixed rate      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 1,198.8 € 2,044.7 € 2,092.2
Unsecured debt | Fixed rate | Weighted average      
Disclosure of financial instruments by type of interest rate [line items]      
Weighted average rate 0.88% 1.70% 1.67%
Unsecured debt | Fixed rate | Less than one year      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 1,198.8 € 848.4 € 50.0
Unsecured debt | Fixed rate | Later than one year and not later than two years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities   1,196.3 843.4
Unsecured debt | Fixed rate | Later than two years and not later than three years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities     1,198.8
Unsecured debt | Floating rate      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 147.8 € 488.9 € 490.0
Unsecured debt | Floating rate | Weighted average      
Disclosure of financial instruments by type of interest rate [line items]      
Weighted average rate 2.44% 2.67% 4.30%
Unsecured debt | Floating rate | Later than three years and not later than four years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 147.8    
Unsecured debt | Floating rate | Thereafter      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities   € 488.9 € 490.0
Debt      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 147.8 1,685.2 2,532.2
Debt | Fixed rate      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 1,198.8 € 2,044.7 € 2,092.2
Debt | Fixed rate | Weighted average      
Disclosure of financial instruments by type of interest rate [line items]      
Weighted average rate 0.88% 1.70% 1.67%
Debt | Fixed rate | Less than one year      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 1,198.8 € 848.4 € 50.0
Debt | Fixed rate | Later than one year and not later than two years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities   1,196.3 843.4
Debt | Fixed rate | Later than two years and not later than three years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities     1,198.8
Lease liabilities - right of use      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 144.9 149.1 164.6
Lease liabilities - right of use | Fixed rate      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 144.9 € 149.1 € 164.6
Lease liabilities - right of use | Fixed rate | Weighted average      
Disclosure of financial instruments by type of interest rate [line items]      
Weighted average rate 4.89% 4.89% 4.43%
Lease liabilities - right of use | Fixed rate | Less than one year      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 39.8 € 37.4 € 39.4
Lease liabilities - right of use | Fixed rate | Later than one year and not later than two years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 39.1 37.9 31.9
Lease liabilities - right of use | Fixed rate | Later than two years and not later than three years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 27.3 38.8 32.1
Lease liabilities - right of use | Fixed rate | Later than three years and not later than four years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 8.6 27.1 32.7
Lease liabilities - right of use | Fixed rate | Thereafter      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 30.1 7.9 28.5
Total fixed rate debt | Fixed rate      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 1,343.7 2,193.8 2,256.8
Total fixed rate debt | Fixed rate | Less than one year      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 1,238.6 885.8 89.4
Total fixed rate debt | Fixed rate | Later than one year and not later than two years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 39.1 1,234.2 875.3
Total fixed rate debt | Fixed rate | Later than two years and not later than three years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 27.3 38.8 1,230.9
Total fixed rate debt | Fixed rate | Later than three years and not later than four years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 8.6 27.1 32.7
Total fixed rate debt | Fixed rate | Thereafter      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 30.1 7.9 28.5
Total floating rate debt | Floating rate      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 147.8 € 488.9 € 490.0
Total floating rate debt | Floating rate | Weighted average      
Disclosure of financial instruments by type of interest rate [line items]      
Weighted average rate 2.44% 2.67% 4.30%
Total floating rate debt | Floating rate | Later than three years and not later than four years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 147.8    
Total floating rate debt | Floating rate | Thereafter      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities   € 488.9 € 490.0
Total financial liabilities      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 1,491.5 2,682.7 2,746.8
Total financial liabilities | Less than one year      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 1,238.6 885.8 89.4
Total financial liabilities | Later than one year and not later than two years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 39.1 1,234.2 875.3
Total financial liabilities | Later than two years and not later than three years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 27.3 38.8 1,230.9
Total financial liabilities | Later than three years and not later than four years      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities 156.4 27.1 32.7
Total financial liabilities | Thereafter      
Disclosure of financial instruments by type of interest rate [line items]      
Financial liabilities € 30.1 € 496.8 € 518.5