Statement Of Cash Flows [Abstract]
| Concept |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
As at 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | ||||||||||||
| Cash flows from (used in) operating activities [abstract] | ||||||||||||
| Profit (loss) |
–
GBP
|
117,700,000
GBP
|
— |
117,700,000
GBP
|
–
GBP
|
–
GBP
|
— |
–
GBP
|
–
GBP
|
60,900,000
GBP
|
–
GBP
|
60,900,000
GBP
|
| Adjustments to reconcile profit (loss) [abstract] | ||||||||||||
| Adjustments for decrease (increase) in inventories | — |
10,800,000
GBP
|
— | — | — | — | — | — | — |
45,400,000
GBP
|
— | — |
| Adjustments for impairment loss (reversal of impairment loss) recognised in profit or loss | — |
–
GBP
|
— | — | — | — | — | — | — |
900,000
GBP
|
— | — |
| Adjustments for provisions | — |
1,400,000
GBP
|
— | — | — | — | — | — | — |
19,500,000
GBP
|
— | — |
| Adjustments for share-based payments | — |
6,600,000
GBP
|
— | — | — | — | — | — | — |
9,700,000
GBP
|
— | — |
| Adjustments for fair value losses (gains) | — |
–
GBP
|
— | — | — | — | — | — | — |
400,000
GBP
|
— | — |
| Cash flows from (used in) operations | — |
221,200,000
GBP
|
— | — | — | — | — | — | — |
75,000,000
GBP
|
— | — |
| Income taxes paid (refund), classified as operating activities | — |
25,200,000
GBP
|
— | — | — | — | — | — | — |
20,300,000
GBP
|
— | — |
| Cash flows from (used in) operating activities | — |
196,000,000
GBP
|
— | — | — | — | — | — | — |
54,700,000
GBP
|
— | — |
| Cash flows from (used in) investing activities [abstract] | ||||||||||||
| Proceeds from sales of property, plant and equipment, classified as investing activities | — |
2,000,000
GBP
|
— | — | — | — | — | — | — |
600,000
GBP
|
— | — |
| Purchase of property, plant and equipment, classified as investing activities | — |
14,300,000
GBP
|
— | — | — | — | — | — | — |
10,500,000
GBP
|
— | — |
| Purchase of intangible assets, classified as investing activities | — |
300,000
GBP
|
— | — | — | — | — | — | — |
1,300,000
GBP
|
— | — |
| Interest received, classified as investing activities | — |
10,000,000
GBP
|
— | — | — | — | — | — | — |
1,800,000
GBP
|
— | — |
| Cash flows from (used in) investing activities | — |
11,000,000
GBP
|
— | — | — | — | — | — | — |
8,300,000
GBP
|
— | — |
| Cash flows from (used in) financing activities [abstract] | ||||||||||||
| Payments to acquire or redeem entity's shares | — |
11,300,000
GBP
|
— | — | — | — | — | — | — |
15,700,000
GBP
|
— | — |
| Repayments of borrowings, classified as financing activities | — |
–
GBP
|
— | — | — | — | — | — | — |
400,000
GBP
|
— | — |
| Payments of lease liabilities, classified as financing activities | — |
21,200,000
GBP
|
— | — | — | — | — | — | — |
17,200,000
GBP
|
— | — |
| Dividends paid, classified as financing activities | — |
48,100,000
GBP
|
— | — | — | — | — | — | — |
43,500,000
GBP
|
— | — |
| Interest paid, classified as financing activities | — |
2,400,000
GBP
|
— | — | — | — | — | — | — |
1,800,000
GBP
|
— | — |
| Cash flows from (used in) financing activities | — |
78,900,000
GBP
|
— | — | — | — | — | — | — |
66,800,000
GBP
|
— | — |
| Increase (decrease) in cash and cash equivalents after effect of exchange rate changes | — |
106,100,000
GBP
|
— | — | — | — | — | — | — |
3,800,000
GBP
|
— | — |
| Cash and cash equivalents | — | — |
541,300,000
GBP
|
— | — | — |
431,700,000
GBP
|
— | — | — | — | — |