Statement Of Financial Position [Abstract]
| Concept |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||||||||||||||||||
| Assets [abstract] | |||||||||||||||||||||||||||||||||
| Non-current assets [abstract] | |||||||||||||||||||||||||||||||||
| Property, plant and equipment |
293,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
283,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Right-of-use assets |
31,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
33,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Goodwill |
177,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
181,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Intangible assets other than goodwill |
4,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
7,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax assets |
17,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
15,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current assets |
530,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
524,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | |||||||||||||||||||||||||||||||||
| Current inventories |
175,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
174,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other current receivables |
191,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
202,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current tax assets, current |
1,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents |
124,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
117,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — |
127,300,000
GBP
|
— | — | — | — | — | — | — |
| Current assets |
493,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
496,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Assets |
1,024,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
1,020,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Equity [abstract] | |||||||||||||||||||||||||||||||||
| Issued capital |
71,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
71,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Retained earnings |
170,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
170,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Share premium |
111,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
111,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent |
360,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
389,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-controlling interests |
38,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
40,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity |
398,600,000
GBP
|
170,800,000
GBP
|
35,700,000
GBP
|
600,000
GBP
|
38,300,000
GBP
|
111,700,000
GBP
|
71,300,000
GBP
|
29,900,000
GBP
|
360,300,000
GBP
|
1,100,000
GBP
|
1,000,000
GBP
|
429,600,000
GBP
|
600,000
GBP
|
40,600,000
GBP
|
111,700,000
GBP
|
35,700,000
GBP
|
170,900,000
GBP
|
71,300,000
GBP
|
–
GBP
|
389,000,000
GBP
|
1,000,000
GBP
|
200,000
GBP
|
109,100,000
GBP
|
35,700,000
GBP
|
600,000
GBP
|
349,600,000
GBP
|
100,000
GBP
|
1,000,000
GBP
|
310,600,000
GBP
|
39,000,000
GBP
|
111,700,000
GBP
|
16,700,000
GBP
|
71,300,000
GBP
|
| Liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Non-current liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Non-current provisions [abstract] | |||||||||||||||||||||||||||||||||
| Non-current provisions for employee benefits |
25,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
15,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current provisions |
11,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
16,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other non-current payables |
2,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
2,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities |
1,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
2,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-current liabilities |
386,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
307,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | |||||||||||||||||||||||||||||||||
| Current provisions [abstract] | |||||||||||||||||||||||||||||||||
| Current provisions |
10,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
9,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Trade and other current payables |
192,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
195,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current tax liabilities, current |
25,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
30,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Current liabilities |
239,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
283,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Liabilities |
626,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
590,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |