Statement Of Cash Flows [Abstract]
| Concept |
As at 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||||||||||||||||||
| Cash flows from (used in) operating activities [abstract] | |||||||||||||||||||||
| Profit (loss) | — |
–
GBP
|
371,800,000
GBP
|
373,000,000
GBP
|
1,200,000
GBP
|
–
GBP
|
–
GBP
|
373,000,000
GBP
|
–
GBP
|
–
GBP
|
1,200,000
GBP
|
–
GBP
|
997,900,000
GBP
|
— |
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
996,700,000
GBP
|
997,900,000
GBP
|
— |
| Adjustments to reconcile profit (loss) [abstract] | |||||||||||||||||||||
| Adjustments for income tax expense | — | — |
97,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
132,500,000
GBP
|
— | — |
| Adjustments for finance costs | — | — |
13,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
12,000,000
GBP
|
— | — |
| Adjustments for share-based payments | — | — |
57,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
65,200,000
GBP
|
— | — |
| Cash flows from (used in) operations | — | — |
556,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
371,300,000
GBP
|
— | — |
| Interest received, classified as operating activities | — | — |
58,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
46,600,000
GBP
|
— | — |
| Income taxes paid (refund), classified as operating activities | — | — |
91,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
126,700,000
GBP
|
— | — |
| Cash flows from (used in) operating activities | — | — |
465,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
244,600,000
GBP
|
— | — |
| Cash flows from (used in) investing activities [abstract] | |||||||||||||||||||||
| Purchase of property, plant and equipment, classified as investing activities | — | — |
98,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
69,200,000
GBP
|
— | — |
| Cash flows from (used in) investing activities | — | — |
101,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
387,800,000
GBP
|
— | — |
| Cash flows from (used in) financing activities [abstract] | |||||||||||||||||||||
| Payments of lease liabilities, classified as financing activities | — | — |
9,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
9,600,000
GBP
|
— | — |
| Dividends paid, classified as financing activities | — | — |
658,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
720,900,000
GBP
|
— | — |
| Interest paid, classified as financing activities | — | — |
25,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
20,200,000
GBP
|
— | — |
| Cash flows from (used in) financing activities | — | — |
425,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
564,800,000
GBP
|
— | — |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — | — |
60,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
67,600,000
GBP
|
— | — |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||||||||||||||||||
| Effect of exchange rate changes on cash and cash equivalents | — | — |
14,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
5,300,000
GBP
|
— | — |
| Cash and cash equivalents |
297,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
372,700,000
GBP
|
— | — | — | — | — | — |
351,700,000
GBP
|