Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2024-12-31 |
As at 2023-12-31 |
As at 2022-12-31 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
481,200,000
GBP
|
504,900,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Other intangible assets |
1 14.4
GBP
|
111. 2
GBP
|
— |
| Goodwill |
207 .0
GBP
|
221 .5
GBP
|
— |
| Trade and other non-current receivables [abstract] | |||
| Trade and other non-current receivables |
2,800,000
GBP
|
1. 3
GBP
|
— |
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables |
141 .3
GBP
|
148,400,000
GBP
|
— |
| Classes of current inventories [abstract] | |||
| Current inventories |
28,100,000
GBP
|
29,500,000
GBP
|
— |
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash [abstract] | |||
| Cash |
19,100,000
GBP
|
45,200,000
GBP
|
— |
| Cash and cash equivalents |
16,000,000
GBP
|
44,700,000
GBP
|
36,200,000
GBP
|
| Borrowings [abstract] | |||
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
87 .4
GBP
|
32,600,000
GBP
|
— |
| Trade and other non-current payables [abstract] | |||
| Other non-current payables |
800,000
GBP
|
900,000
GBP
|
— |
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
146,700,000
GBP
|
122,700,000
GBP
|
— |
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
11. 3
GBP
|
11. 1
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
31 .6
GBP
|
33,100,000
GBP
|
— |
| Retained earnings [abstract] | |||
| Retained earnings |
290,400,000
GBP
|
404,000,000
GBP
|
— |
| Accumulated other comprehensive income [abstract] | |||
| Reserve of exchange differences on translation |
38,800,000
GBP
|
52,300,000
GBP
|
— |
| Miscellaneous equity [abstract] | |||
| Capital redemption reserve |
131 .3
GBP
|
129,800,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
1,067 .4
GBP
|
1,136,700,000
GBP
|
— |
| Liabilities |
397 .5
GBP
|
344,400,000
GBP
|
— |
| Assets (liabilities) |
669,900,000
GBP
|
792,300,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
198,600,000
GBP
|
236,700,000
GBP
|
— |
| Current liabilities |
291 .3
GBP
|
225,100,000
GBP
|
— |
| Current assets (liabilities) |
92,700,000
GBP
|
11. 6
GBP
|
— |
| Assets less current liabilities [abstract] |