Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2025-03-31 |
As at 2024-03-31 |
As at 2023-03-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
5,849,400,000
GBP
|
5,374,300,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets other than goodwill |
62,200,000
GBP
|
60,300,000
GBP
|
— |
| Goodwill |
179,900,000
GBP
|
179,900,000
GBP
|
— |
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in subsidiaries reported in separate financial statements |
–
GBP
|
–
GBP
|
— |
| Investments in associates reported in separate financial statements |
1,800,000
GBP
|
1,000,000
GBP
|
— |
| Miscellaneous non-current assets [abstract] | |||
| Non-current net defined benefit asset |
22,000,000
GBP
|
26,600,000
GBP
|
— |
| Non-current derivative financial assets |
22,400,000
GBP
|
17,400,000
GBP
|
— |
| Other non-current assets |
8,700,000
GBP
|
8,700,000
GBP
|
— |
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables |
391,800,000
GBP
|
355,400,000
GBP
|
— |
| Categories of non-current financial assets [abstract] | |||
| Non-current financial assets at fair value through profit or loss [abstract] | |||
| Non-current financial assets at fair value through profit or loss |
600,000
GBP
|
900,000
GBP
|
— |
| Classes of current inventories [abstract] | |||
| Current inventories |
12,800,000
GBP
|
13,200,000
GBP
|
— |
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
417,900,000
GBP
|
134,000,000
GBP
|
132,300,000
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current net defined benefit asset |
9,200,000
GBP
|
–
GBP
|
— |
| Current restricted cash and cash equivalents |
58,200,000
GBP
|
37,400,000
GBP
|
— |
| Current derivative financial assets |
9,800,000
GBP
|
23,400,000
GBP
|
— |
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
4,296,900,000
GBP
|
3,775,500,000
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
257,400,000
GBP
|
240,700,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
331,000,000
GBP
|
346,500,000
GBP
|
— |
| Categories of current financial liabilities [abstract] | |||
| Current financial liabilities at fair value through profit or loss [abstract] | |||
| Current financial liabilities at fair value through profit or loss |
300,000
GBP
|
100,000
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current derivative financial liabilities |
1,600,000
GBP
|
3,300,000
GBP
|
— |
| Other non-current liabilities |
171,300,000
GBP
|
154,900,000
GBP
|
— |
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
500,000
GBP
|
5,400,000
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
288,100,000
GBP
|
174,600,000
GBP
|
— |
| Miscellaneous equity [abstract] | |||
| Capital redemption reserve |
157,100,000
GBP
|
157,100,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets (liabilities) |
1,450,700,000
GBP
|
1,162,600,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
900,600,000
GBP
|
569,400,000
GBP
|
— |
| Current liabilities |
596,000,000
GBP
|
592,700,000
GBP
|
— |
| Current assets (liabilities) |
304,600,000
GBP
|
23,300,000
GBP
|
— |
| Assets less current liabilities [abstract] |