Statement Of Cash Flows [Abstract]
| Concept |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-01-01 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-01-01 |
|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | ||||||||
| Cash flows from (used in) operating activities [abstract] | ||||||||
| Profit (loss) | — |
119,500,000
GBP
|
119,500,000
GBP
|
— |
77,400,000
GBP
|
— |
77,400,000
GBP
|
— |
| Cash flows from (used in) operations | — |
73,100,000
GBP
|
— | — | — | — |
76,900,000
GBP
|
— |
| Interest paid, classified as operating activities | — |
24,300,000
GBP
|
— | — | — | — |
22,100,000
GBP
|
— |
| Interest received, classified as operating activities | — |
500,000
GBP
|
— | — | — | — |
1,000,000
GBP
|
— |
| Income taxes paid (refund), classified as operating activities | — |
5,100,000
GBP
|
— | — | — | — |
11,500,000
GBP
|
— |
| Cash flows from (used in) operating activities | — |
44,200,000
GBP
|
— | — | — | — |
44,300,000
GBP
|
— |
| Cash flows from (used in) investing activities [abstract] | ||||||||
| Cash flows from losing control of subsidiaries or other businesses, classified as investing activities | — |
–
GBP
|
— | — | — | — |
1,400,000
GBP
|
— |
| Purchase of property, plant and equipment, classified as investing activities | — |
600,000
GBP
|
— | — | — | — |
300,000
GBP
|
— |
| Purchase of intangible assets, classified as investing activities | — |
900,000
GBP
|
— | — | — | — |
800,000
GBP
|
— |
| Cash receipts from futures contracts, forward contracts, option contracts and swap contracts, classified as investing activities | — |
–
GBP
|
— | — | — | — |
300,000
GBP
|
— |
| Dividends received, classified as investing activities | — |
200,000
GBP
|
— | — | — | — |
100,000
GBP
|
— |
| Income taxes paid (refund), classified as investing activities | — |
1,300,000
GBP
|
— | — | — | — |
9,000,000
GBP
|
— |
| Cash flows from (used in) investing activities | — |
165,500,000
GBP
|
— | — | — | — |
92,400,000
GBP
|
— |
| Cash flows from (used in) financing activities [abstract] | ||||||||
| Proceeds from borrowings, classified as financing activities | — |
196,700,000
GBP
|
— | — | — | — |
182,500,000
GBP
|
— |
| Repayments of borrowings, classified as financing activities | — |
107,200,000
GBP
|
— | — | — | — |
128,300,000
GBP
|
— |
| Dividends paid, classified as financing activities | — |
30,800,000
GBP
|
— | — | — | — |
30,100,000
GBP
|
— |
| Cash flows from (used in) financing activities | — |
57,300,000
GBP
|
— | — | — | — |
21,600,000
GBP
|
— |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — |
64,000,000
GBP
|
— | — | — | — |
26,500,000
GBP
|
— |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | ||||||||
| Effect of exchange rate changes on cash and cash equivalents | — |
4,300,000
GBP
|
— | — | — | — |
2,800,000
GBP
|
— |
| Increase (decrease) in cash and cash equivalents after effect of exchange rate changes | — |
68,300,000
GBP
|
— | — | — | — |
23,700,000
GBP
|
— |
| Cash and cash equivalents |
167,400,000
GBP
|
— | — |
235,700,000
GBP
|
— |
235,700,000
GBP
|
— |
259,400,000
GBP
|