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 |
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 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2019-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||||||||||||
| Cash flows from (used in) operating activities [abstract] | |||||||||||||||
| Profit (loss) | — |
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
7 8 7. 2
GBP
|
7 8 7. 2
GBP
|
638,400,000
GBP
|
— |
–
GBP
|
638,400,000
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
— |
| Adjustments to reconcile profit (loss) [abstract] | |||||||||||||||
| Adjustments for income tax expense | — | — | — | — | — |
1 79.6
GBP
|
— | — | — | — |
145,400,000
GBP
|
— | — | — | — |
| Adjustments for finance costs | — | — | — | — | — |
3,600,000
GBP
|
— | — | — | — |
8 .6
GBP
|
— | — | — | — |
| Adjustments for decrease (increase) in inventories | — | — | — | — | — |
9,800,000
GBP
|
— | — | — | — |
265,000,000
GBP
|
— | — | — | — |
| Adjustments for impairment loss (reversal of impairment loss) recognised in profit or loss | — | — | — | — | — |
6,200,000
GBP
|
— | — | — | — |
4. 3
GBP
|
— | — | — | — |
| Adjustments for provisions | — | — | — | — | — |
–
GBP
|
— | — | — | — |
75,000,000
GBP
|
— | — | — | — |
| Adjustments for share-based payments | — | — | — | — | — |
6,400,000
GBP
|
— | — | — | — |
6 .4
GBP
|
— | — | — | — |
| Other adjustments for non-cash items | — | — | — | — | — |
7. 9
GBP
|
— | — | — | — |
7. 3
GBP
|
— | — | — | — |
| Cash flows from (used in) operations | — | — | — | — | — |
972 .8
GBP
|
— | — | — | — |
993. 3
GBP
|
— | — | — | — |
| Interest paid, classified as operating activities | — | — | — | — | — |
3. 7
GBP
|
— | — | — | — |
4 .1
GBP
|
— | — | — | — |
| Interest received, classified as operating activities | — | — | — | — | — |
1,900,000
GBP
|
— | — | — | — |
4,700,000
GBP
|
— | — | — | — |
| Income taxes paid (refund), classified as operating activities | — | — | — | — | — |
1 86. 2
GBP
|
— | — | — | — |
228 .4
GBP
|
— | — | — | — |
| Cash flows from (used in) operating activities | — | — | — | — | — |
784,800,000
GBP
|
— | — | — | — |
765. 5
GBP
|
— | — | — | — |
| Cash flows from (used in) investing activities [abstract] | |||||||||||||||
| Proceeds from sales of property, plant and equipment, classified as investing activities | — | — | — | — | — |
900,000
GBP
|
— | — | — | — |
800,000
GBP
|
— | — | — | — |
| Purchase of property, plant and equipment, classified as investing activities | — | — | — | — | — |
20. 9
GBP
|
— | — | — | — |
18,900,000
GBP
|
— | — | — | — |
| Cash flows from (used in) investing activities | — | — | — | — | — |
18 .2
GBP
|
— | — | — | — |
1 8 .1
GBP
|
— | — | — | — |
| Cash flows from (used in) financing activities [abstract] | |||||||||||||||
| Payments of lease liabilities, classified as financing activities | — | — | — | — | — |
3,300,000
GBP
|
— | — | — | — |
3,600,000
GBP
|
— | — | — | — |
| Dividends paid, classified as financing activities | — | — | — | — | — |
74 9 .6
GBP
|
— | — | — | — |
3 50.7
GBP
|
— | — | — | — |
| Cash flows from (used in) financing activities | — | — | — | — | — |
7 5 4 .1
GBP
|
— | — | — | — |
3 5 7. 2
GBP
|
— | — | — | — |
| Increase (decrease) in cash and cash equivalents after effect of exchange rate changes | — | — | — | — | — |
12,500,000
GBP
|
— | — | — | — |
390. 2
GBP
|
— | — | — | — |
| Cash and cash equivalents |
1 , 24 6 .6
GBP
|
— | — | — | — | — | — | — |
1 , 23 4 .1
GBP
|
— | — | — | — | — |
8 43.9
GBP
|