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 |
|---|---|---|---|---|
| Statement of cash flows [abstract] | ||||
| Cash flows from (used in) operating activities [abstract] | ||||
| Income taxes paid (refund), classified as operating activities | — |
181,400,000
GBP
|
— |
153,800,000
GBP
|
| Cash flows from (used in) operating activities | — |
733,100,000
GBP
|
— |
790,200,000
GBP
|
| Cash flows from (used in) investing activities [abstract] | ||||
| Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities | — |
436,700,000
GBP
|
— |
363,200,000
GBP
|
| Proceeds from sales of property, plant and equipment, classified as investing activities | — |
2,700,000
GBP
|
— |
1,200,000
GBP
|
| Purchase of property, plant and equipment, classified as investing activities | — |
32,700,000
GBP
|
— |
33,100,000
GBP
|
| Interest received, classified as investing activities | — |
8,700,000
GBP
|
— |
15,100,000
GBP
|
| Cash flows from (used in) investing activities | — |
458,000,000
GBP
|
— |
380,000,000
GBP
|
| Cash flows from (used in) financing activities [abstract] | ||||
| Payments to acquire or redeem entity's shares | — |
34,200,000
GBP
|
— |
49,100,000
GBP
|
| Proceeds from borrowings, classified as financing activities | — |
14,500,000
GBP
|
— |
444,500,000
GBP
|
| Repayments of borrowings, classified as financing activities | — |
134,900,000
GBP
|
— |
133,500,000
GBP
|
| Payments of lease liabilities, classified as financing activities | — |
158,900,000
GBP
|
— |
159,600,000
GBP
|
| Dividends paid, classified as financing activities | — |
180,400,000
GBP
|
— |
171,500,000
GBP
|
| Interest paid, classified as financing activities | — |
43,500,000
GBP
|
— |
56,600,000
GBP
|
| Cash flows from (used in) financing activities | — |
458,700,000
GBP
|
— |
122,200,000
GBP
|
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — |
183,600,000
GBP
|
— |
2 88.0
GBP
|
| Effect of exchange rate changes on cash and cash equivalents [abstract] | ||||
| Effect of exchange rate changes on cash and cash equivalents | — |
20,800,000
GBP
|
— |
900,000
GBP
|
| Cash and cash equivalents |
776,900,000
GBP
|
— |
944,300,000
GBP
|
— |