Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2023-03-31 |
As at 2022-03-31 |
As at 2021-03-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
3,000,000
GBP
|
3,000,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets other than goodwill |
5,000,000
GBP
|
6,000,000
GBP
|
— |
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in subsidiaries reported in separate financial statements |
7,844,000,000
GBP
|
6,791,000,000
GBP
|
— |
| Miscellaneous non-current assets [abstract] | |||
| Non-current net defined benefit asset |
53,000,000
GBP
|
53,000,000
GBP
|
— |
| Non-current derivative financial assets |
73,000,000
GBP
|
7,000,000
GBP
|
— |
| Other non-current assets |
30,000,000
GBP
|
45,000,000
GBP
|
— |
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
162,000,000
GBP
|
212,000,000
GBP
|
216,000,000
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
48,000,000
GBP
|
10,000,000
GBP
|
— |
| Other current assets |
30,000,000
GBP
|
104,000,000
GBP
|
— |
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
775,000,000
GBP
|
775,000,000
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
–
GBP
|
200,000,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Trade and other non-current payables |
4,000,000
GBP
|
14,000,000
GBP
|
— |
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
76,000,000
GBP
|
80,000,000
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
20,000,000
GBP
|
26,000,000
GBP
|
— |
| Non-current derivative financial liabilities |
3,000,000
GBP
|
–
GBP
|
— |
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
1,000,000
GBP
|
–
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
719,000,000
GBP
|
719,000,000
GBP
|
— |
| Retained earnings [abstract] | |||
| Retained earnings |
1,327,000,000
GBP
|
1,125,000,000
GBP
|
— |
| Accumulated other comprehensive income [abstract] | |||
| Reserve of exchange differences on translation |
2,000,000
GBP
|
6,000,000
GBP
|
— |
| Miscellaneous equity [abstract] | |||
| Reserve of share-based payments |
31,000,000
GBP
|
33,000,000
GBP
|
— |
| Capital redemption reserve |
43,000,000
GBP
|
43,000,000
GBP
|
— |
| Capital reserve |
14,044,000,000
GBP
|
10,151,000,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
17,819,000,000
GBP
|
13,948,000,000
GBP
|
— |
| Liabilities |
975,000,000
GBP
|
1,194,000,000
GBP
|
— |
| Assets (liabilities) |
16,844,000,000
GBP
|
12,754,000,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
281,000,000
GBP
|
378,000,000
GBP
|
— |
| Current liabilities |
120,000,000
GBP
|
324,000,000
GBP
|
— |
| Assets less current liabilities [abstract] |