Statement Of Financial Position [Abstract]
| Concept |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
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 2004-04-01 |
As at 2004-04-01 |
As at 2004-04-01 |
As at 2004-04-01 |
As at 2003-04-01 |
As at 2001-04-01 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||||||||||||
| Assets [abstract] | |||||||||||||||||||||||||||
| Non-current assets [abstract] | |||||||||||||||||||||||||||
| Property, plant and equipment | — |
1,354,806,000
GBP
|
— | — | — | — | — | — | — | — | — |
1,253,349,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Right-of-use assets | — |
336,221,000
GBP
|
— | — | — | — | — | — | — | — | — |
327,551,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Goodwill | — |
2,029,620,000
GBP
|
— | — | — | — | — | — | — | — | — |
1,765,961,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Intangible assets other than goodwill | — |
928,009,000
GBP
|
— | — | — | — | — | — | — | — | — |
868,488,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Investments accounted for using equity method | — |
47,789,000
GBP
|
— | — | — | — | — | — | — | — | — |
26,843,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax assets | — |
69,053,000
GBP
|
— | — | — | — | — | — | — | — | — |
54,494,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current assets | — |
4,854,697,000
GBP
|
— | — | — | — | — | — | — | — | — |
4,415,264,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | |||||||||||||||||||||||||||
| Current inventories | — |
1,192,803,000
GBP
|
— | — | — | — | — | — | — | — | — |
1,133,666,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other current receivables | — |
2,312,269,000
GBP
|
— | — | — | — | — | — | — | — | — |
2,508,613,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — |
1,421,749,000
GBP
|
— | — | — | — | — | — | — | — | — |
1,394,272,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current assets | — |
4,986,079,000
GBP
|
— | — | — | — | — | — | — | — | — |
5,143,912,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Assets | — |
9,840,776,000
GBP
|
— | — | — | — | — | — | — | — | — |
9,559,176,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | |||||||||||||||||||||||||||
| Equity [abstract] | |||||||||||||||||||||||||||
| Issued capital | — |
17,422,000
GBP
|
— | — | — | — | — | — | — | — | — |
17,422,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Retained earnings | — |
1,941,223,000
GBP
|
— | — | — | — | — | — | — | — | — |
1,783,033,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Share premium | — |
883,669,000
GBP
|
— | — | — | — | — | — | — | — | — |
883,321,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Other reserves | — |
932,000
GBP
|
— | — | — | — | — | — | — | — | — |
932,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent | — |
2,978,091,000
GBP
|
— | — | — | — | — | — | — | — | — |
2,905,184,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-controlling interests | — |
80,219,000
GBP
|
— | — | — | — | — | — | — | — | — |
65,379,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity |
2,978,091,000
GBP
|
3,058,310,000
GBP
|
883,669,000
GBP
|
17,422,000
GBP
|
80,219,000
GBP
|
1,941,223,000
GBP
|
135,777,000
GBP
|
2,905,184,000
GBP
|
17,422,000
GBP
|
883,321,000
GBP
|
1,783,033,000
GBP
|
2,970,563,000
GBP
|
65,379,000
GBP
|
221,408,000
GBP
|
1,631,797,000
GBP
|
115,291,000
GBP
|
2,705,644,000
GBP
|
17,422,000
GBP
|
882,924,000
GBP
|
58,210,000
GBP
|
2,647,434,000
GBP
|
221,408,000
GBP
|
65,379,000
GBP
|
2,905,184,000
GBP
|
883,321,000
GBP
|
1,783,033,000
GBP
|
17,422,000
GBP
|
| Liabilities [abstract] | |||||||||||||||||||||||||||
| Non-current liabilities [abstract] | |||||||||||||||||||||||||||
| Non-current provisions [abstract] | |||||||||||||||||||||||||||
| Non-current provisions | — |
301,067,000
GBP
|
— | — | — | — | — | — | — | — | — |
284,191,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — |
263,623,000
GBP
|
— | — | — | — | — | — | — | — | — |
259,796,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current liabilities | — |
2,889,319,000
GBP
|
— | — | — | — | — | — | — | — | — |
2,826,224,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | |||||||||||||||||||||||||||
| Current provisions [abstract] | |||||||||||||||||||||||||||
| Current provisions | — |
52,349,000
GBP
|
— | — | — | — | — | — | — | — | — |
50,279,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other current payables | — |
3,279,898,000
GBP
|
— | — | — | — | — | — | — | — | — |
3,468,705,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current liabilities | — |
3,893,147,000
GBP
|
— | — | — | — | — | — | — | — | — |
3,762,389,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Liabilities | — |
6,782,466,000
GBP
|
— | — | — | — | — | — | — | — | — |
6,588,613,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities | — |
9,840,776,000
GBP
|
— | — | — | — | — | — | — | — | — |
9,559,176,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |