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 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||||||||||||
| Assets [abstract] | |||||||||||||||||||||||||||
| Property, plant and equipment |
96,100,000
GBP
|
— | — | — | — | — | — | — | — |
94,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
90,000,000
GBP
|
— | — | — | — | — |
| Right-of-use assets |
104,500,000
GBP
|
— | — | — | — | — | — | — | — |
119,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
138,100,000
GBP
|
— | — | — | — | — |
| Current tax assets |
12,500,000
GBP
|
— | — | — | — | — | — | — | — |
14,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
8,800,000
GBP
|
— | — | — | — | — |
| Deferred tax assets |
11,600,000
GBP
|
— | — | — | — | — | — | — | — |
11,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
30,200,000
GBP
|
— | — | — | — | — |
| Cash and cash equivalents |
471,200,000
GBP
|
— | — | — | — | — | — | — | — |
264,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
273,200,000
GBP
|
— | — | — | — | — |
| Assets |
3,058,000,000
GBP
|
— | — | — | — | — | — | — | — |
3,244,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
2,693,400,000
GBP
|
— | — | — | — | — |
| Equity and liabilities [abstract] | |||||||||||||||||||||||||||
| Equity [abstract] | |||||||||||||||||||||||||||
| Issued capital |
9,300,000
GBP
|
— | — | — | — | — | — | — | — |
9,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
9,300,000
GBP
|
— | — | — | — | — |
| Retained earnings |
1,041,600,000
GBP
|
— | — | — | — | — | — | — | — |
854,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
762,300,000
GBP
|
— | — | — | — | — |
| Share premium |
4,000,000
GBP
|
— | — | — | — | — | — | — | — |
4,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
4,000,000
GBP
|
— | — | — | — | — |
| Treasury shares |
140,400,000
GBP
|
— | — | — | — | — | — | — | — |
127,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
115,500,000
GBP
|
— | — | — | — | — |
| Equity attributable to owners of parent |
941,700,000
GBP
|
— | — | — | — | — | — | — | — |
865,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
740,500,000
GBP
|
— | — | — | — | — |
| Non-controlling interests |
7,700,000
GBP
|
— | — | — | — | — | — | — | — |
6,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
4,300,000
GBP
|
— | — | — | — | — |
| Equity |
949,400,000
GBP
|
1,041,600,000
GBP
|
–
GBP
|
7,700,000
GBP
|
4,000,000
GBP
|
9,300,000
GBP
|
27,200,000
GBP
|
140,400,000
GBP
|
941,700,000
GBP
|
872,000,000
GBP
|
6,300,000
GBP
|
4,000,000
GBP
|
75,000,000
GBP
|
854,400,000
GBP
|
127,700,000
GBP
|
9,300,000
GBP
|
50,700,000
GBP
|
865,700,000
GBP
|
115,500,000
GBP
|
762,300,000
GBP
|
75,000,000
GBP
|
744,800,000
GBP
|
5,400,000
GBP
|
740,500,000
GBP
|
4,000,000
GBP
|
4,300,000
GBP
|
9,300,000
GBP
|
| Liabilities [abstract] | |||||||||||||||||||||||||||
| Current tax liabilities |
16,900,000
GBP
|
— | — | — | — | — | — | — | — |
30,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
27,400,000
GBP
|
— | — | — | — | — |
| Deferred tax liabilities |
13,400,000
GBP
|
— | — | — | — | — | — | — | — |
20,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
25,800,000
GBP
|
— | — | — | — | — |
| Liabilities |
2,108,600,000
GBP
|
— | — | — | — | — | — | — | — |
2,372,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
1,948,600,000
GBP
|
— | — | — | — | — |