Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2021-12-31 |
As at 2020-12-31 |
As at 2019-12-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
5 48.0
GBP
|
5 6 9. 8
GBP
|
695. 1
GBP
|
| Intangible assets and goodwill [abstract] | |||
| Intangible assets and goodwill |
394,100,000
GBP
|
4 25.8
GBP
|
554,400,000
GBP
|
| Investments accounted for using equity method [abstract] | |||
| Investments accounted for using equity method |
4 .9
GBP
|
2. 4
GBP
|
4,300,000
GBP
|
| Trade and other non-current receivables [abstract] | |||
| Trade and other non-current receivables |
45. 4
GBP
|
4 9. 2
GBP
|
3 8.7
GBP
|
| Miscellaneous non-current assets [abstract] | |||
| Non-current net defined benefit asset |
13 5 . 3
GBP
|
1 01. 0
GBP
|
78,700,000
GBP
|
| Non-current derivative financial assets |
3,000,000
GBP
|
–
GBP
|
–
GBP
|
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables |
3 2 4 .1
GBP
|
3 6 9. 6
GBP
|
512 . 3
GBP
|
| Categories of non-current financial assets [abstract] | |||
| Non-current financial assets at fair value through other comprehensive income [abstract] | |||
| Non-current financial assets at fair value through other comprehensive income |
4,800,000
GBP
|
3,600,000
GBP
|
6 .9
GBP
|
| Categories of current financial assets [abstract] | |||
| Current financial assets at fair value through other comprehensive income [abstract] | |||
| Current financial assets at fair value through other comprehensive income |
200,000
GBP
|
200,000
GBP
|
0. 2
GBP
|
| Classes of current inventories [abstract] | |||
| Current inventories |
1,13 4 . 7
GBP
|
1, 216 . 2
GBP
|
1 ,566. 9
GBP
|
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash [abstract] | |||
| Cash |
5 0 1. 8
GBP
|
3 78.5
GBP
|
— |
| Cash equivalents [abstract] | |||
| Short-term deposits, classified as cash equivalents |
94. 6
GBP
|
10 2 .7
GBP
|
— |
| Cash and cash equivalents |
596. 4
GBP
|
4 81. 2
GBP
|
423,000,000
GBP
|
| Non-current assets or disposal groups classified as held for sale or as held for distribution to owners [abstract] | |||
| Non-current assets or disposal groups classified as held for sale |
4,800,000
GBP
|
31 . 2
GBP
|
14 9. 4
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
24,600,000
GBP
|
13 . 3
GBP
|
16 . 2
GBP
|
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
210 . 0
GBP
|
21 0 . 0
GBP
|
27 0. 0
GBP
|
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
7. 6
GBP
|
6 .1
GBP
|
5 0.1
GBP
|
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Trade and other non-current payables |
6 3 . 2
GBP
|
69 .3
GBP
|
7 7. 2
GBP
|
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
1, 5 4 8 . 3
GBP
|
1 , 61 0 . 3
GBP
|
1,9 9 6 . 4
GBP
|
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
5 3 . 1
GBP
|
81. 4
GBP
|
6 9. 2
GBP
|
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
31,900,000
GBP
|
4 2 . 4
GBP
|
2 7. 4
GBP
|
| Issued capital [abstract] | |||
| Issued capital |
38,500,000
GBP
|
3 9. 4
GBP
|
4 0.0
GBP
|
| Retained earnings [abstract] | |||
| Retained earnings |
1, 0 0 8 . 7
GBP
|
9 62.8
GBP
|
1 ,1 2 0 . 5
GBP
|
| Miscellaneous equity [abstract] | |||
| Capital redemption reserve |
142 .1
GBP
|
14 1. 2
GBP
|
14 0 . 6
GBP
|
| Net assets (liabilities) [abstract] | |||
| Assets |
3 , 5 5 8 .1
GBP
|
3 , 6 11 . 9
GBP
|
4 , 4 41.9
GBP
|
| Liabilities |
2 , 4 2 7. 6
GBP
|
2 ,5 5 0 .7
GBP
|
3 ,16 4 . 2
GBP
|
| Assets (liabilities) |
1,13 0 . 5
GBP
|
1 , 0 61. 2
GBP
|
1, 2 7 7. 7
GBP
|
| Net current assets (liabilities) [abstract] | |||
| Current assets |
2,093,800,000
GBP
|
2 ,13 2 . 3
GBP
|
2 , 6 8 9. 6
GBP
|
| Current liabilities |
1, 74 2 . 2
GBP
|
1, 81 6 . 8
GBP
|
2, 34 2. 2
GBP
|
| Assets less current liabilities [abstract] |