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 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||
| Property, plant and equipment | — | — | — | — |
1,238,000,000
GBP
|
— | — |
1,424,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Right-of-use assets | — | — | — | — |
61,000,000
GBP
|
— | — |
74,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Goodwill | — | — | — | — |
366,000,000
GBP
|
— | — |
554,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Intangible assets other than goodwill | — | — | — | — |
267,000,000
GBP
|
— | — |
359,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Investments accounted for using equity method | — | — | — | — |
2,000,000
GBP
|
— | — |
2,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Deferred tax assets | — | — | — | — |
98,000,000
GBP
|
— | — |
140,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Non-current assets | — | — | — | — |
2,482,000,000
GBP
|
— | — |
2,870,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||
| Current inventories | — | — | — | — |
1,549,000,000
GBP
|
— | — |
1,814,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Trade and other current receivables | — | — | — | — |
1,796,000,000
GBP
|
— | — |
2,422,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Other current financial assets | — | — | — | — |
27,000,000
GBP
|
— | — |
44,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — | — |
391,000,000
GBP
|
— | — |
581,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current assets | — | — | — | — |
4,184,000,000
GBP
|
— | — |
4,874,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Assets | — | — | — | — |
6,666,000,000
GBP
|
— | — |
7,744,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital | — | — | — | — |
218,000,000
GBP
|
— | — |
221,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Retained earnings | — | — | — | — |
2,049,000,000
GBP
|
— | — |
2,345,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Share premium | — | — | — | — |
148,000,000
GBP
|
— | — |
148,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Other reserves | — | — | — | — |
50,000,000
GBP
|
— | — |
–
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Equity |
24,000,000
GBP
|
218,000,000
GBP
|
148,000,000
GBP
|
2,049,000,000
GBP
|
2,441,000,000
GBP
|
50,000,000
GBP
|
2,345,000,000
GBP
|
2,685,000,000
GBP
|
221,000,000
GBP
|
148,000,000
GBP
|
2 9
GBP
|
–
GBP
|
142,000,000
GBP
|
2,824,000,000
GBP
|
32,000,000
GBP
|
148,000,000
GBP
|
221,000,000
GBP
|
2,345,000,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||
| Non-current provisions | — | — | — | — |
28,000,000
GBP
|
— | — |
27,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — | — |
18,000,000
GBP
|
— | — |
28,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Non-current liabilities | — | — | — | — |
1,073,000,000
GBP
|
— | — |
1,461,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||
| Current provisions [abstract] | ||||||||||||||||||
| Current provisions | — | — | — | — |
56,000,000
GBP
|
— | — |
35,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Trade and other current payables | — | — | — | — |
2,563,000,000
GBP
|
— | — |
3,325,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Other current financial liabilities | — | — | — | — |
4 4
GBP
|
— | — |
1 8
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Liabilities included in disposal groups classified as held for sale | — | — | — | — |
8 0
GBP
|
— | — |
–
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current liabilities | — | — | — | — |
3,152,000,000
GBP
|
— | — |
3,598,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Liabilities | — | — | — | — |
4,225,000,000
GBP
|
— | — |
5,059,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |