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 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||
| Property, plant and equipment |
988,100,000
GBP
|
— | — | — | — | — |
900,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Right-of-use assets |
87,900,000
GBP
|
— | — | — | — | — |
80,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Investments accounted for using equity method |
3,300,000
GBP
|
— | — | — | — | — |
5,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Deferred tax assets |
13,500,000
GBP
|
— | — | — | — | — |
14,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Non-current assets |
2,399,700,000
GBP
|
— | — | — | — | — |
2,329,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||
| Current inventories |
443,000,000
GBP
|
— | — | — | — | — |
302,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Trade and other current receivables |
337,900,000
GBP
|
— | — | — | — | — |
289,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents |
112,800,000
GBP
|
— | — | — | — | — |
106,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current assets |
893,700,000
GBP
|
— | — | — | — | — |
699,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital |
16,200,000
GBP
|
— | — | — | — | — |
16,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Share premium |
707,700,000
GBP
|
— | — | — | — | — |
707,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Other reserves |
1,029,200,000
GBP
|
— | — | — | — | — |
861,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent |
1,753,100,000
GBP
|
— | — | — | — | — |
1,585,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Non-controlling interests |
12,800,000
GBP
|
— | — | — | — | — |
9,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity |
1,765,900,000
GBP
|
1,073,000,000
GBP
|
43,800,000
GBP
|
707,700,000
GBP
|
12,800,000
GBP
|
16,200,000
GBP
|
1,595,100,000
GBP
|
16,200,000
GBP
|
842,600,000
GBP
|
9,300,000
GBP
|
19,300,000
GBP
|
707,700,000
GBP
|
718,800,000
GBP
|
7,000,000
GBP
|
34,400,000
GBP
|
868,600,000
GBP
|
93,300,000
GBP
|
15,100,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||
| Non-current provisions |
3,600,000
GBP
|
— | — | — | — | — |
3,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities |
151,400,000
GBP
|
— | — | — | — | — |
160,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Non-current liabilities |
1,067,600,000
GBP
|
— | — | — | — | — |
1,088,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||
| Current provisions [abstract] | ||||||||||||||||||
| Current provisions |
5,500,000
GBP
|
— | — | — | — | — |
6,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Trade and other current payables |
358,000,000
GBP
|
— | — | — | — | — |
240,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current liabilities |
459,900,000
GBP
|
— | — | — | — | — |
345,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |