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 |
293,800,000
GBP
|
283,200,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets other than goodwill |
4,700,000
GBP
|
7,100,000
GBP
|
— |
| Goodwill |
177,500,000
GBP
|
181,900,000
GBP
|
— |
| Trade and other non-current receivables [abstract] | |||
| Other non-current receivables |
3,400,000
GBP
|
3,200,000
GBP
|
— |
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables |
191,600,000
GBP
|
202,500,000
GBP
|
— |
| Classes of current inventories [abstract] | |||
| Current inventories |
175,100,000
GBP
|
174,200,000
GBP
|
— |
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
124,500,000
GBP
|
117,700,000
GBP
|
127,300,000
GBP
|
| Miscellaneous current assets [abstract] | |||
| Current derivative financial assets |
1,500,000
GBP
|
1,300,000
GBP
|
— |
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
309,100,000
GBP
|
230,100,000
GBP
|
— |
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
600,000
GBP
|
36,100,000
GBP
|
— |
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Trade and other non-current payables |
2,400,000
GBP
|
2,100,000
GBP
|
— |
| Trade and other current payables [abstract] | |||
| Trade and other current payables |
192,000,000
GBP
|
195,000,000
GBP
|
— |
| Miscellaneous current liabilities [abstract] | |||
| Current derivative financial liabilities |
500,000
GBP
|
1,600,000
GBP
|
— |
| Issued capital [abstract] | |||
| Issued capital |
71,300,000
GBP
|
71,300,000
GBP
|
— |
| Retained earnings [abstract] | |||
| Retained earnings |
170,800,000
GBP
|
170,900,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
1,024,700,000
GBP
|
1,020,300,000
GBP
|
— |
| Liabilities |
626,100,000
GBP
|
590,700,000
GBP
|
— |
| Assets (liabilities) |
398,600,000
GBP
|
429,600,000
GBP
|
— |
| Net current assets (liabilities) [abstract] | |||
| Current assets |
493,900,000
GBP
|
496,000,000
GBP
|
— |
| Current liabilities |
239,500,000
GBP
|
283,400,000
GBP
|
— |
| Assets less current liabilities [abstract] |