Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2024-03-31 |
As at 2023-03-31 |
As at 2022-03-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
4,000,000
GBP
|
3,000,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets other than goodwill |
4,000,000
GBP
|
5,000,000
GBP
|
— |
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in subsidiaries reported in separate financial statements |
5,804,000,000
GBP
|
7,844,000,000
GBP
|
— |
| Miscellaneous non-current assets [abstract] | |||
| Non-current net defined benefit asset |
61,000,000
GBP
|
53,000,000
GBP
|
— |
| Non-current derivative financial assets |
83,000,000
GBP
|
73,000,000
GBP
|
— |
| Other non-current assets |
28,000,000
GBP
|
30,000,000
GBP
|
— |
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
358,000,000
GBP
|
162,000,000
GBP
|
212,000,000
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
82,000,000
GBP
|
48,000,000
GBP
|
— |
| Other current assets |
47,000,000
GBP
|
30,000,000
GBP
|
— |
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
1,202,000,000
GBP
|
775,000,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Trade and other non-current payables |
5,000,000
GBP
|
4,000,000
GBP
|
— |
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
134,000,000
GBP
|
76,000,000
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
21,000,000
GBP
|
20,000,000
GBP
|
— |
| Non-current derivative financial liabilities |
–
GBP
|
3,000,000
GBP
|
— |
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
–
GBP
|
1,000,000
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
719,000,000
GBP
|
719,000,000
GBP
|
— |
| Retained earnings [abstract] | |||
| Retained earnings |
1,519,000,000
GBP
|
1,327,000,000
GBP
|
— |
| Accumulated other comprehensive income [abstract] | |||
| Reserve of exchange differences on translation |
6,000,000
GBP
|
2,000,000
GBP
|
— |
| Miscellaneous equity [abstract] | |||
| Reserve of share-based payments |
42,000,000
GBP
|
31,000,000
GBP
|
— |
| Capital redemption reserve |
43,000,000
GBP
|
43,000,000
GBP
|
— |
| Capital reserve |
17,154,000,000
GBP
|
14,044,000,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
21,641,000,000
GBP
|
17,819,000,000
GBP
|
— |
| Liabilities |
1,471,000,000
GBP
|
975,000,000
GBP
|
— |
| Assets (liabilities) |
20,170,000,000
GBP
|
16,844,000,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
533,000,000
GBP
|
281,000,000
GBP
|
— |
| Current liabilities |
165,000,000
GBP
|
120,000,000
GBP
|
— |
| Assets less current liabilities [abstract] |