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] | ||||||||||||||||||||||||
| 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
|
— | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — | — |
61,200,000
GBP
|
— | — | — | — | — | — | — | — | — |
60,800,000
GBP
|
— | — | — |
33,400,000
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] | ||||||||||||||||||||||||
| Current tax liabilities | — | — | — | — |
1,000,000
GBP
|
— | — | — | — | — | — | — | — | — |
200,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — | — |
10,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
8,700,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Liabilities | — | — | — | — |
240,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
247,400,000
GBP
|
— | — | — | — | — | — | — | — | — |