Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2023-12-31 |
As at 2022-12-31 |
As at 2021-12-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
96,100,000
GBP
|
94,100,000
GBP
|
90,000,000
GBP
|
| Intangible assets and goodwill [abstract] | |||
| Intangible assets and goodwill |
322,400,000
GBP
|
342,100,000
GBP
|
273,700,000
GBP
|
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in associates reported in separate financial statements |
100,000
GBP
|
100,000
GBP
|
100,000
GBP
|
| Trade and other non-current receivables [abstract] | |||
| Non-current prepayments and non-current accrued income other than non-current contract assets [abstract] | |||
| Non-current prepayments |
10,300,000
GBP
|
19,400,000
GBP
|
16,600,000
GBP
|
| Trade and other non-current receivables |
21,100,000
GBP
|
9,900,000
GBP
|
–
GBP
|
| Non-current prepayments and non-current accrued income including non-current contract assets [abstract] | |||
| Trade and other current receivables [abstract] | |||
| Current prepayments and current accrued income other than current contract assets [abstract] | |||
| Current prepayments [abstract] | |||
| Current prepayments |
139,700,000
GBP
|
130,500,000
GBP
|
103,000,000
GBP
|
| Trade and other current receivables |
1,498,100,000
GBP
|
1,683,800,000
GBP
|
1,254,700,000
GBP
|
| Current prepayments and current accrued income including current contract assets [abstract] | |||
| Current accrued income including current contract assets [abstract] | |||
| Current accrued income including current contract assets |
151,900,000
GBP
|
129,200,000
GBP
|
148,100,000
GBP
|
| Classes of current inventories [abstract] | |||
| Current inventories |
216,000,000
GBP
|
417,700,000
GBP
|
341,300,000
GBP
|
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash [abstract] | |||
| Cash |
471,200,000
GBP
|
264,400,000
GBP
|
285,200,000
GBP
|
| Cash and cash equivalents |
471,200,000
GBP
|
264,400,000
GBP
|
273,200,000
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
2,500,000
GBP
|
7,500,000
GBP
|
3,600,000
GBP
|
| Trade and other non-current payables [abstract] | |||
| Non-current accruals and non-current deferred income including non-current contract liabilities [abstract] | |||
| Non-current deferred income including non-current contract liabilities [abstract] | |||
| Non-current deferred income including non-current contract liabilities |
4,300,000
GBP
|
7,900,000
GBP
|
8,300,000
GBP
|
| Trade and other current payables [abstract] | |||
| Current accruals and current deferred income including current contract liabilities [abstract] | |||
| Current deferred income including current contract liabilities [abstract] | |||
| Current deferred income including current contract liabilities |
230,300,000
GBP
|
265,300,000
GBP
|
249,300,000
GBP
|
| Trade and other current payables |
1,674,500,000
GBP
|
1,857,500,000
GBP
|
1,410,400,000
GBP
|
| Categories of non-current financial liabilities [abstract] | |||
| Non-current financial liabilities |
7,400,000
GBP
|
12,600,000
GBP
|
16,700,000
GBP
|
| Categories of current financial liabilities [abstract] | |||
| Current financial liabilities |
4,800,000
GBP
|
7,500,000
GBP
|
15,100,000
GBP
|
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
26,200,000
GBP
|
23,000,000
GBP
|
21,800,000
GBP
|
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
6,300,000
GBP
|
8,700,000
GBP
|
2,500,000
GBP
|
| Issued capital [abstract] | |||
| Issued capital |
9,300,000
GBP
|
9,300,000
GBP
|
9,300,000
GBP
|
| Retained earnings [abstract] | |||
| Retained earnings |
1,041,600,000
GBP
|
854,400,000
GBP
|
762,300,000
GBP
|
| Miscellaneous equity [abstract] | |||
| Capital redemption reserve |
–
GBP
|
75,000,000
GBP
|
75,000,000
GBP
|
| Net assets (liabilities) [abstract] | |||
| Assets |
3,058,000,000
GBP
|
3,244,000,000
GBP
|
2,693,400,000
GBP
|
| Liabilities |
2,108,600,000
GBP
|
2,372,000,000
GBP
|
1,948,600,000
GBP
|
| Assets (liabilities) |
949,400,000
GBP
|
872,000,000
GBP
|
744,800,000
GBP
|
| Net current assets (liabilities) [abstract] | |||
| Current assets |
2,491,900,000
GBP
|
2,647,700,000
GBP
|
2,144,700,000
GBP
|
| Current liabilities |
1,972,300,000
GBP
|
2,210,600,000
GBP
|
1,763,200,000
GBP
|
| Assets less current liabilities [abstract] |