Statement Of Financial Position [Abstract]
| Concept |
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 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||||||||
| Property, plant and equipment | — | — | — |
44,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
47,400,000
GBP
|
— | — | — | — | — | — | — | — |
| Goodwill | — | — | — |
570,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
570,600,000
GBP
|
— | — | — | — | — | — | — | — |
| Intangible assets other than goodwill | — | — | — |
52,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
70,800,000
GBP
|
— | — | — | — | — | — | — | — |
| Trade and other non-current receivables | — | — | — |
500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
500,000
GBP
|
— | — | — | — | — | — | — | — |
| Deferred tax assets | — | — | — |
27,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
20,000,000
GBP
|
— | — | — | — | — | — | — | — |
| Non-current assets | — | — | — |
694,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
709,300,000
GBP
|
— | — | — | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||||||||
| Trade and other current receivables | — | — | — |
145,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
187,300,000
GBP
|
— | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — |
197,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
188,100,000
GBP
|
— | — | — | — |
179,400,000
GBP
|
— | — | — |
| Current assets | — | — | — |
645,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
636,500,000
GBP
|
— | — | — | — | — | — | — | — |
| Assets | — | — | — |
1,340,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
1,345,800,000
GBP
|
— | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||||||||
| Issued capital | — | — | — |
11,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
11,100,000
GBP
|
— | — | — | — | — | — | — | — |
| Retained earnings | — | — | — |
639,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
622,500,000
GBP
|
— | — | — | — | — | — | — | — |
| Treasury shares | — | — | — |
400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
200,000
GBP
|
— | — | — | — | — | — | — | — |
| Other reserves | — | — | — |
250,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
250,100,000
GBP
|
— | — | — | — | — | — | — | — |
| Equity attributable to owners of parent | — | — | — |
900,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
886,300,000
GBP
|
— | — | — | — | — | — | — | — |
| Non-controlling interests | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
200,000
GBP
|
— | — | — | — | — | — | — | — |
| Equity |
400,000
GBP
|
639,700,000
GBP
|
250,100,000
GBP
|
900,800,000
GBP
|
900,800,000
GBP
|
–
GBP
|
300,000
GBP
|
11,100,000
GBP
|
622,500,000
GBP
|
200,000
GBP
|
886,300,000
GBP
|
11,100,000
GBP
|
200,000
GBP
|
2,800,000
GBP
|
250,100,000
GBP
|
886,100,000
GBP
|
611,700,000
GBP
|
–
GBP
|
8,000,000
GBP
|
2,100,000
GBP
|
611,700,000
GBP
|
592,700,000
GBP
|
300,000
GBP
|
9,200,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||||||||
| Trade and other non-current payables | — | — | — |
102,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
87,400,000
GBP
|
— | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — |
10,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
12,500,000
GBP
|
— | — | — | — | — | — | — | — |
| Non-current liabilities | — | — | — |
161,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
149,100,000
GBP
|
— | — | — | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||||||||
| Trade and other current payables | — | — | — |
222,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
212,800,000
GBP
|
— | — | — | — | — | — | — | — |
| Current liabilities | — | — | — |
278,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
310,600,000
GBP
|
— | — | — | — | — | — | — | — |
| Liabilities | — | — | — |
439,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
459,700,000
GBP
|
— | — | — | — | — | — | — | — |
| Equity and liabilities | — | — | — |
1,340,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
1,345,800,000
GBP
|
— | — | — | — | — | — | — | — |