Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2023-12-31 |
As at 2023-01-01 |
As at 2022-12-31 |
As at 2022-01-01 |
|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||
| Property, plant and equipment [abstract] | ||||
| Property, plant and equipment |
20,100,000
GBP
|
— |
20,900,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | ||||
| Intangible assets other than goodwill [abstract] | ||||
| Intangible assets other than goodwill |
409,300,000
GBP
|
— |
456,000,000
GBP
|
— |
| Goodwill |
827,600,000
GBP
|
— |
804,700,000
GBP
|
— |
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | ||||
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements |
562,700,000
GBP
|
— |
552,400,000
GBP
|
— |
| Investments accounted for using equity method [abstract] | ||||
| Investments in joint ventures accounted for using equity method |
562,600,000
GBP
|
— |
552,300,000
GBP
|
— |
| Trade and other non-current receivables [abstract] | ||||
| Trade and other non-current receivables |
-
GBP
|
— |
1,000,000
GBP
|
— |
| Trade and other current receivables [abstract] | ||||
| Trade and other current receivables |
626,400,000
GBP
|
— |
542,100,000
GBP
|
— |
| Classes of current inventories [abstract] | ||||
| Current inventories |
3,100,700,000
GBP
|
— |
2,838,100,000
GBP
|
— |
| Classes of current inventories, alternative [abstract] | ||||
| Cash and cash equivalents [abstract] | ||||
| Cash and cash equivalents |
4 18.3
GBP
|
67 6.8
GBP
|
67 6.8
GBP
|
398,700,000
GBP
|
| Miscellaneous assets [abstract] | ||||
| Net defined benefit asset |
34,200,000
GBP
|
— |
34,300,000
GBP
|
— |
| Borrowings [abstract] | ||||
| Non-current portion of non-current borrowings |
507,100,000
GBP
|
— |
508,700,000
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | ||||
| Current borrowings |
-
GBP
|
— |
49,900,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | ||||
| Trade and other non-current payables [abstract] | ||||
| Trade and other non-current payables |
341,000,000
GBP
|
— |
334,500,000
GBP
|
— |
| Trade and other current payables [abstract] | ||||
| Trade and other current payables |
1,481,900,000
GBP
|
— |
1,432,700,000
GBP
|
— |
| Issued capital [abstract] | ||||
| Issued capital |
17 3.4
GBP
|
— |
17 3.6
GBP
|
— |
| Retained earnings [abstract] | ||||
| Retained earnings |
1,184,800,000
GBP
|
— |
1,116,200,000
GBP
|
— |
| Miscellaneous equity [abstract] | ||||
| Capital redemption reserve |
1,500,000
GBP
|
— |
1,300,000
GBP
|
— |
| Merger reserve |
1,597,800,000
GBP
|
— |
1,597,800,000
GBP
|
— |
| Net assets (liabilities) [abstract] | ||||
| Assets |
6,085,400,000
GBP
|
— |
6,015,700,000
GBP
|
— |
| Liabilities |
2,7 66.9
GBP
|
— |
2,7 66.0
GBP
|
— |
| Net current assets (liabilities) [abstract] | ||||
| Current assets |
4,148,600,000
GBP
|
— |
4,067,400,000
GBP
|
— |
| Current liabilities |
1,611,500,000
GBP
|
— |
1,570,300,000
GBP
|
— |
| Assets less current liabilities [abstract] |