Statement Of Cash Flows [Abstract]
| Concept |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-01-01 |
As at 2019-12-31 |
|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | ||||||
| Cash flows from (used in) operating activities [abstract] | ||||||
| Cash flows from (used in) operations | — |
75,400,000
GBP
|
— |
100,500,000
GBP
|
— | — |
| Income taxes paid (refund), classified as operating activities | — |
12,200,000
GBP
|
— |
7,700,000
GBP
|
— | — |
| Cash flows from (used in) operating activities | — |
63,200,000
GBP
|
— |
92,800,000
GBP
|
— | — |
| Cash flows from (used in) investing activities [abstract] | ||||||
| Cash flows from losing control of subsidiaries or other businesses, classified as investing activities | — |
-
GBP
|
— |
5,000,000
GBP
|
— | — |
| Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities | — |
14,600,000
GBP
|
— |
41,200,000
GBP
|
— | — |
| Proceeds from sales of property, plant and equipment, classified as investing activities | — |
8,900,000
GBP
|
— |
400,000
GBP
|
— | — |
| Purchase of property, plant and equipment, classified as investing activities | — |
38,500,000
GBP
|
— |
30,900,000
GBP
|
— | — |
| Purchase of intangible assets, classified as investing activities | — |
3,200,000
GBP
|
— |
3,700,000
GBP
|
— | — |
| Interest received, classified as investing activities | — |
400,000
GBP
|
— |
1,900,000
GBP
|
— | — |
| Cash flows from (used in) investing activities | — |
47,000,000
GBP
|
— |
67,900,000
GBP
|
— | — |
| Cash flows from (used in) financing activities [abstract] | ||||||
| Proceeds from issuing shares | — |
-
GBP
|
— |
100,000,000
GBP
|
— | — |
| Payments of lease liabilities, classified as financing activities | — |
12,800,000
GBP
|
— |
11,900,000
GBP
|
— | — |
| Interest paid, classified as financing activities | — |
11,000,000
GBP
|
— |
14,700,000
GBP
|
— | — |
| Cash flows from (used in) financing activities | — |
13,700,000
GBP
|
— |
40,400,000
GBP
|
— | — |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — |
2,500,000
GBP
|
— |
65,300,000
GBP
|
— | — |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | ||||||
| Effect of exchange rate changes on cash and cash equivalents | — |
2,000,000
GBP
|
— |
100,000
GBP
|
— | — |
| Cash and cash equivalents |
136,300,000
GBP
|
— |
135,800,000
GBP
|
— |
70,400,000
GBP
|
70,400,000
GBP
|