Statement Of Financial Position [Abstract]
| Concept |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
As at 2020-03-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||||||||||||||||||
| Assets [abstract] | |||||||||||||||||||||||||||||||||
| Non-current assets [abstract] | |||||||||||||||||||||||||||||||||
| Property, plant and equipment | — | — | — | — | — | — | — | — | — |
4 385
GBP
|
— | — | — |
4 052
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Investments accounted for using equity method | — | — | — | — | — | — | — | — | — |
165,000,000
GBP
|
— | — | — |
171,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax assets | — | — | — | — | — | — | — | — | — |
32,000,000
GBP
|
— | — | — |
34,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current assets | — | — | — | — | — | — | — | — | — |
5 733
GBP
|
— | — | — |
5 440
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | |||||||||||||||||||||||||||||||||
| Current inventories | — | — | — | — | — | — | — | — | — |
97,000,000
GBP
|
— | — | — |
109,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other current receivables | — | — | — | — | — | — | — | — | — |
834,000,000
GBP
|
— | — | — |
826,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — | — | — | — | — | — | — |
534,000,000
GBP
|
— | — | — |
294,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — |
329,000,000
GBP
|
— | — | — | — | — |
| Current assets | — | — | — | — | — | — | — | — | — |
1 474
GBP
|
— | — | — |
1 232
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Assets | — | — | — | — | — | — | — | — | — |
7 207
GBP
|
— | — | — |
6 672
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Equity [abstract] | |||||||||||||||||||||||||||||||||
| Issued capital | — | — | — | — | — | — | — | — | — |
74,000,000
GBP
|
— | — | — |
74,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Retained earnings | — | — | — | — | — | — | — | — | — |
4 597
GBP
|
— | — | — |
4 523
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Share premium | — | — | — | — | — | — | — | — | — |
690,000,000
GBP
|
— | — | — |
69 0
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Other reserves | — | — | — | — | — | — | — | — | — |
2 254
GBP
|
— | — | — |
2 438
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent | — | — | — | — | — | — | — | — | — |
3 107
GBP
|
— | — | — |
2 849
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-controlling interests | — | — | — | — | — | — | — | — | — |
139,000,000
GBP
|
— | — | — |
118,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity |
6,000,000
GBP
|
3 014
GBP
|
4,000,000
GBP
|
3 107
GBP
|
2,000,000
GBP
|
74,000,000
GBP
|
752,000,000
GBP
|
690,000,000
GBP
|
4 597
GBP
|
3 246
GBP
|
139,000,000
GBP
|
6,000,000
GBP
|
4 523
GBP
|
2 967
GBP
|
74,000,000
GBP
|
690,000,000
GBP
|
–
GBP
|
8,000,000
GBP
|
118,000,000
GBP
|
3 014
GBP
|
2 849
GBP
|
578,000,000
GBP
|
113,000,000
GBP
|
2 890
GBP
|
–
GBP
|
3 014
GBP
|
815,000,000
GBP
|
3 003
GBP
|
6,000,000
GBP
|
690,000,000
GBP
|
8,000,000
GBP
|
74,000,000
GBP
|
4 327
GBP
|
| Liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Non-current liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Non-current provisions [abstract] | |||||||||||||||||||||||||||||||||
| Non-current provisions | — | — | — | — | — | — | — | — | — |
37,000,000
GBP
|
— | — | — |
37,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — | — | — | — | — | — | — |
432,000,000
GBP
|
— | — | — |
425,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current liabilities | — | — | — | — | — | — | — | — | — |
3 138
GBP
|
— | — | — |
3 021
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Current provisions [abstract] | |||||||||||||||||||||||||||||||||
| Current provisions | — | — | — | — | — | — | — | — | — |
38,000,000
GBP
|
— | — | — |
19,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other current payables | — | — | — | — | — | — | — | — | — |
586,000,000
GBP
|
— | — | — |
49 8
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current liabilities | — | — | — | — | — | — | — | — | — |
823,000,000
GBP
|
— | — | — |
684,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Liabilities | — | — | — | — | — | — | — | — | — |
3 961
GBP
|
— | — | — |
3 705
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities | — | — | — | — | — | — | — | — | — |
7 207
GBP
|
— | — | — |
6 672
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |