Statement Of Financial Position [Abstract]
| Concept |
As at 2025-03-31 |
As at 2025-03-31 |
As at 2025-03-31 |
As at 2025-03-31 |
As at 2025-03-31 |
As at 2025-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||
| Property, plant and equipment | — | — |
5,849,400,000
GBP
|
— | — | — | — | — | — | — | — |
5,374,300,000
GBP
|
— | — | — | — | — | — |
| Goodwill | — | — |
179,900,000
GBP
|
— | — | — | — | — | — | — | — |
179,900,000
GBP
|
— | — | — | — | — | — |
| Intangible assets other than goodwill | — | — |
62,200,000
GBP
|
— | — | — | — | — | — | — | — |
60,300,000
GBP
|
— | — | — | — | — | — |
| Deferred tax assets | — | — |
–
GBP
|
— | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — |
| Non-current assets | — | — |
6,147,000,000
GBP
|
— | — | — | — | — | — | — | — |
5,669,100,000
GBP
|
— | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||
| Current inventories | — | — |
12,800,000
GBP
|
— | — | — | — | — | — | — | — |
13,200,000
GBP
|
— | — | — | — | — | — |
| Trade and other current receivables | — | — |
391,800,000
GBP
|
— | — | — | — | — | — | — | — |
355,400,000
GBP
|
— | — | — | — | — | — |
| Cash and cash equivalents | — | — |
417,900,000
GBP
|
— | — | — | — | — | — | — | — |
134,000,000
GBP
|
— | — |
132,300,000
GBP
|
— | — | — |
| Current assets | — | — |
900,600,000
GBP
|
— | — | — | — | — | — | — | — |
569,400,000
GBP
|
— | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital | — | — |
288,100,000
GBP
|
— | — | — | — | — | — | — | — |
174,600,000
GBP
|
— | — | — | — | — | — |
| Share premium | — | — |
755,000,000
GBP
|
— | — | — | — | — | — | — | — |
398,200,000
GBP
|
— | — | — | — | — | — |
| Equity attributable to owners of parent | — | — |
1,448,200,000
GBP
|
— | — | — | — | — | — | — | — |
1,161,200,000
GBP
|
— | — | — | — | — | — |
| Non-controlling interests | — | — |
2,500,000
GBP
|
— | — | — | — | — | — | — | — |
1,400,000
GBP
|
— | — | — | — | — | — |
| Equity |
288,100,000
GBP
|
248,000,000
GBP
|
1,450,700,000
GBP
|
2,500,000
GBP
|
157,100,000
GBP
|
755,000,000
GBP
|
431,300,000
GBP
|
1,400,000
GBP
|
398,200,000
GBP
|
174,600,000
GBP
|
157,100,000
GBP
|
1,162,600,000
GBP
|
570,600,000
GBP
|
237,600,000
GBP
|
1,125,200,000
GBP
|
400,000
GBP
|
159,500,000
GBP
|
157,100,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||
| Non-current provisions | — | — |
500,000
GBP
|
— | — | — | — | — | — | — | — |
1,100,000
GBP
|
— | — | — | — | — | — |
| Deferred tax liabilities | — | — |
530,600,000
GBP
|
— | — | — | — | — | — | — | — |
548,400,000
GBP
|
— | — | — | — | — | — |
| Non-current liabilities | — | — |
5,000,900,000
GBP
|
— | — | — | — | — | — | — | — |
4,483,200,000
GBP
|
— | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||
| Current provisions [abstract] | ||||||||||||||||||
| Current provisions | — | — |
6,800,000
GBP
|
— | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — |
| Trade and other current payables | — | — |
331,000,000
GBP
|
— | — | — | — | — | — | — | — |
346,500,000
GBP
|
— | — | — | — | — | — |
| Current liabilities | — | — |
596,000,000
GBP
|
— | — | — | — | — | — | — | — |
592,700,000
GBP
|
— | — | — | — | — | — |