Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2023-12-31 |
As at 2022-12-31 |
As at 2022-01-01 |
As at 2021-12-31 |
|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||
| Property, plant and equipment [abstract] | ||||
| Property, plant and equipment |
353,700,000
GBP
|
369,900,000
GBP
|
355,500,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | ||||
| Intangible assets and goodwill |
1,577,600,000
GBP
|
1,394,600,000
GBP
|
1,384,100,000
GBP
|
— |
| Trade and other non-current receivables [abstract] | ||||
| Trade and other non-current receivables |
5,300,000
GBP
|
6,300,000
GBP
|
2,100,000
GBP
|
— |
| Trade and other current receivables [abstract] | ||||
| Trade and other current receivables |
322,200,000
GBP
|
245,700,000
GBP
|
243,400,000
GBP
|
— |
| Classes of current inventories [abstract] | ||||
| Current inventories |
272,700,000
GBP
|
286,200,000
GBP
|
196,800,000
GBP
|
— |
| Classes of current inventories, alternative [abstract] | ||||
| Cash and cash equivalents [abstract] | ||||
| Cash and cash equivalents |
392,400,000
GBP
|
583,300,000
GBP
|
418,900,000
GBP
|
418,900,000
GBP
|
| Borrowings [abstract] | ||||
| Non-current portion of non-current borrowings |
980,300,000
GBP
|
1,104,000,000
GBP
|
1,074,900,000
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | ||||
| Current borrowings |
89,400,000
GBP
|
107,100,000
GBP
|
114,300,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | ||||
| Trade and other non-current payables [abstract] | ||||
| Trade and other non-current payables |
122,300,000
GBP
|
43,200,000
GBP
|
43,900,000
GBP
|
— |
| Trade and other current payables [abstract] | ||||
| Trade and other current payables |
840,400,000
GBP
|
891,200,000
GBP
|
735,900,000
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | ||||
| Non-current net defined benefit liability |
49,000,000
GBP
|
61,200,000
GBP
|
78,700,000
GBP
|
— |
| Issued capital [abstract] | ||||
| Issued capital |
82,400,000
GBP
|
69,900,000
GBP
|
11,600,000
GBP
|
— |
| Retained earnings [abstract] | ||||
| Retained earnings |
1,437,700,000
GBP
|
1,233,900,000
GBP
|
711,400,000
GBP
|
— |
| Accumulated other comprehensive income [abstract] | ||||
| Reserve of exchange differences on translation |
2,500,000
GBP
|
6,500,000
GBP
|
2,700,000
GBP
|
— |
| Reserve of cash flow hedges |
800,000
GBP
|
4,300,000
GBP
|
6,700,000
GBP
|
— |
| Miscellaneous equity [abstract] | ||||
| Capital redemption reserve |
9,300,000
GBP
|
9,300,000
GBP
|
9,300,000
GBP
|
— |
| Merger reserve |
143,900,000
GBP
|
143,900,000
GBP
|
143,900,000
GBP
|
— |
| Capital reserve |
6,600,000
GBP
|
6,600,000
GBP
|
6,600,000
GBP
|
— |
| Net assets (liabilities) [abstract] | ||||
| Assets |
3,173,000,000
GBP
|
3,104,300,000
GBP
|
2,842,500,000
GBP
|
— |
| Liabilities |
2,249,900,000
GBP
|
2,380,800,000
GBP
|
2,231,100,000
GBP
|
— |
| Assets (liabilities) |
923,100,000
GBP
|
723,500,000
GBP
|
611,400,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | ||||
| Current assets |
991,500,000
GBP
|
1,125,400,000
GBP
|
867,900,000
GBP
|
— |
| Current liabilities |
986,100,000
GBP
|
1,056,800,000
GBP
|
920,100,000
GBP
|
— |
| Assets less current liabilities [abstract] |