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 |
44,300,000
GBP
|
48,100,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets other than goodwill |
115,600,000
GBP
|
158,000,000
GBP
|
— |
| Goodwill |
906,700,000
GBP
|
945,000,000
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 |
32,100,000
GBP
|
23,300,000
GBP
|
— |
| Trade and other non-current receivables [abstract] | |||
| Trade and other non-current receivables |
14,800,000
GBP
|
16,100,000
GBP
|
— |
| Miscellaneous non-current assets [abstract] | |||
| Non-current net defined benefit asset |
37,400,000
GBP
|
57,000,000
GBP
|
— |
| Non-current derivative financial assets |
—
GBP
|
300,000
GBP
|
— |
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables |
329,000,000
GBP
|
374,600,000
GBP
|
— |
| Current prepayments and current accrued income including current contract assets [abstract] | |||
| Current accrued income including current contract assets [abstract] | |||
| Current contract assets |
296,600,000
GBP
|
345,000,000
GBP
|
— |
| Categories of non-current financial assets [abstract] | |||
| Non-current loans and receivables |
—
GBP
|
10,000,000
GBP
|
— |
| Categories of current financial assets [abstract] | |||
| Current loans and receivables |
10,000,000
GBP
|
—
GBP
|
— |
| Classes of current inventories [abstract] | |||
| Current inventories |
24,100,000
GBP
|
22,400,000
GBP
|
— |
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
94,400,000
GBP
|
57,200,000
GBP
|
198,400,000
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
4,900,000
GBP
|
3,300,000
GBP
|
— |
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
155,200,000
GBP
|
218,400,000
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
51,000,000
GBP
|
44,500,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | |||
| 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 contract liabilities [abstract] | |||
| Non-current contract liabilities |
59,300,000
GBP
|
36,300,000
GBP
|
— |
| Trade and other non-current payables |
9,200,000
GBP
|
6,500,000
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 contract liabilities [abstract] | |||
| Current contract liabilities |
35,800,000
GBP
|
60,500,000
GBP
|
— |
| Trade and other current payables |
558,000,000
GBP
|
622,800,000
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
12,900,000
GBP
|
6,200,000
GBP
|
— |
| Non-current derivative financial liabilities |
200,000
GBP
|
—
GBP
|
— |
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
1,700,000
GBP
|
1,100,000
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
22,100,000
GBP
|
24,400,000
GBP
|
— |
| Retained earnings [abstract] | |||
| Retained earnings |
659,100,000
GBP
|
670,600,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
2,610,300,000
GBP
|
2,750,200,000
GBP
|
— |
| Liabilities |
1,576,600,000
GBP
|
1,720,500,000
GBP
|
— |
| Assets (liabilities) |
1,033,700,000
GBP
|
1,029,700,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
782,800,000
GBP
|
814,000,000
GBP
|
— |
| Current liabilities |
897,800,000
GBP
|
1,024,200,000
GBP
|
— |
| Assets less current liabilities [abstract] |