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 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Property, plant and equipment | — | — | — |
1,044,000,000
GBP
|
— | — |
964,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Right-of-use assets | — | — | — |
87,500,000
GBP
|
— | — |
96,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Investments accounted for using equity method | — | — | — |
1,900,000
GBP
|
— | — |
3,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Deferred tax assets | — | — | — |
14,400,000
GBP
|
— | — |
10,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — |
172,500,000
GBP
|
— | — |
320,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital | — | — | — |
15,100,000
GBP
|
— | — |
15,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Share premium | — | — | — |
707,700,000
GBP
|
— | — |
707,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Other reserves | — | — | — |
1,629,700,000
GBP
|
— | — |
1,692,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent | — | — | — |
2,352,500,000
GBP
|
— | — |
2,415,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Non-controlling interests | — | — | — |
15,600,000
GBP
|
— | — |
15,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity |
707,700,000
GBP
|
15,100,000
GBP
|
1,640,000,000
GBP
|
2,368,100,000
GBP
|
10,300,000
GBP
|
15,600,000
GBP
|
2,431,100,000
GBP
|
707,700,000
GBP
|
15,500,000
GBP
|
1,645,700,000
GBP
|
15,100,000
GBP
|
47,100,000
GBP
|
1,073,000,000
GBP
|
1,765,900,000
GBP
|
43,800,000
GBP
|
707,700,000
GBP
|
12,800,000
GBP
|
16,200,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||
| Current tax liabilities | — | — | — |
9,200,000
GBP
|
— | — |
26,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — |
192,800,000
GBP
|
— | — |
172,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |