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 | — | — | — | — |
113,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
122,900,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Right-of-use assets | — | — | — | — |
35,000,000
GBP
|
— | — | — | — | — | — | — | — | — |
42,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Investment property | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — |
| Trade and other non-current receivables | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — |
| Non-current assets | — | — | — | — |
166,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
186,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||||||||
| Current inventories | — | — | — | — |
130,900,000
GBP
|
— | — | — | — | — | — | — | — | — |
118,500,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Trade and other current receivables | — | — | — | — |
114,000,000
GBP
|
— | — | — | — | — | — | — | — | — |
101,600,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — | — |
61,200,000
GBP
|
— | — | — | — | — | — | — | — | — |
60,800,000
GBP
|
— | — | — |
33,400,000
GBP
|
— | — | — | — | — |
| Current assets other than non-current assets or disposal groups classified as held for sale or as held for distribution to owners | — | — | — | — |
306,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
280,900,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current assets | — | — | — | — |
306,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
281,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Assets | — | — | — | — |
472,500,000
GBP
|
— | — | — | — | — | — | — | — | — |
467,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||||||||
| Issued capital | — | — | — | — |
4,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
4,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Retained earnings | — | — | — | — |
175,900,000
GBP
|
— | — | — | — | — | — | — | — | — |
158,800,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Share premium | — | — | — | — |
53,500,000
GBP
|
— | — | — | — | — | — | — | — | — |
53,500,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Other reserves | — | — | — | — |
1,600,000
GBP
|
— | — | — | — | — | — | — | — | — |
3,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Equity |
4,900,000
GBP
|
175,900,000
GBP
|
100,000
GBP
|
1,500,000
GBP
|
232,100,000
GBP
|
53,500,000
GBP
|
1,700,000
GBP
|
4,300,000
GBP
|
158,800,000
GBP
|
1,500,000
GBP
|
4,300,000
GBP
|
5,900,000
GBP
|
7,700,000
GBP
|
53,500,000
GBP
|
220,000,000
GBP
|
100,000
GBP
|
6,800,000
GBP
|
53,500,000
GBP
|
245,100,000
GBP
|
500,000
GBP
|
186,000,000
GBP
|
6,100,000
GBP
|
100,000
GBP
|
4,300,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||||||||
| Non-current provisions | — | — | — | — |
2,700,000
GBP
|
— | — | — | — | — | — | — | — | — |
2,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — | — |
10,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
8,700,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Non-current liabilities | — | — | — | — |
49,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
54,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||||||||
| Trade and other current payables | — | — | — | — |
178,000,000
GBP
|
— | — | — | — | — | — | — | — | — |
178,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current liabilities | — | — | — | — |
191,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
193,100,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Liabilities | — | — | — | — |
240,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
247,400,000
GBP
|
— | — | — | — | — | — | — | — | — |