Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2022-03-31 |
As at 2021-03-31 |
As at 2020-03-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
3,000,000
GBP
|
5,000,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets and goodwill |
6,000,000
GBP
|
8,000,000
GBP
|
— |
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in subsidiaries reported in separate financial statements |
6 ,791
GBP
|
4 ,9 0 5
GBP
|
— |
| Miscellaneous non-current assets [abstract] | |||
| Non-current net defined benefit asset |
53,000,000
GBP
|
55,000,000
GBP
|
— |
| Non-current derivative financial assets |
7,000,000
GBP
|
16,000,000
GBP
|
— |
| Other non-current assets |
45,000,000
GBP
|
52,000,000
GBP
|
— |
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
2 12
GBP
|
2 16
GBP
|
7 71
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
10,000,000
GBP
|
10,000,000
GBP
|
— |
| Other current assets |
10 4
GBP
|
21,000,000
GBP
|
— |
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
7 75
GBP
|
97 5
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
20 0
GBP
|
–
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Trade and other non-current payables |
14,000,000
GBP
|
17,000,000
GBP
|
— |
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
80,000,000
GBP
|
6 2
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
26,000,000
GBP
|
29,000,000
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
7 19
GBP
|
719,000,000
GBP
|
— |
| Retained earnings [abstract] | |||
| Retained earnings |
1,1 2 5
GBP
|
9 16
GBP
|
— |
| Accumulated other comprehensive income [abstract] | |||
| Reserve of exchange differences on translation |
6,000,000
GBP
|
5,000,000
GBP
|
— |
| Miscellaneous equity [abstract] | |||
| Reserve of share-based payments |
33,000,000
GBP
|
34,000,000
GBP
|
— |
| Capital redemption reserve |
43,000,000
GBP
|
43,000,000
GBP
|
— |
| Capital reserve |
1 0 ,1 5 1
GBP
|
6 ,73 3
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
13 ,9 4 8
GBP
|
10, 3 3 4
GBP
|
— |
| Liabilities |
1 ,1 9 4
GBP
|
1,1 7 0
GBP
|
— |
| Assets (liabilities) |
12 , 7 5 4
GBP
|
9,1 6 4
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
378,000,000
GBP
|
257,000,000
GBP
|
— |
| Current liabilities |
324,000,000
GBP
|
8 4
GBP
|
— |
| Assets less current liabilities [abstract] |