Statement Of Cash Flows [Abstract]
| Concept |
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 |
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 |
As at 2021-12-31 |
|---|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||||||
| Cash flows from (used in) operating activities [abstract] | |||||||||
| Profit (loss) |
202,400,000
GBP
|
— |
29,100,000
GBP
|
173,300,000
GBP
|
— |
155,000,000
GBP
|
13,700,000
GBP
|
168,700,000
GBP
|
— |
| Cash flows from (used in) operating activities |
393,100,000
GBP
|
— | — | — | — |
327,200,000
GBP
|
— | — | — |
| Cash flows from (used in) investing activities [abstract] | |||||||||
| Cash flows from losing control of subsidiaries or other businesses, classified as investing activities |
200,000
GBP
|
— | — | — | — |
—
GBP
|
— | — | — |
| Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities |
7,700,000
GBP
|
— | — | — | — |
19,200,000
GBP
|
— | — | — |
| Proceeds from sales of property, plant and equipment, classified as investing activities |
1,400,000
GBP
|
— | — | — | — |
700,000
GBP
|
— | — | — |
| Purchase of property, plant and equipment, classified as investing activities |
15,900,000
GBP
|
— | — | — | — |
12,400,000
GBP
|
— | — | — |
| Proceeds from sales of intangible assets, classified as investing activities |
1,300,000
GBP
|
— | — | — | — |
—
GBP
|
— | — | — |
| Purchase of intangible assets, classified as investing activities |
8,800,000
GBP
|
— | — | — | — |
7,000,000
GBP
|
— | — | — |
| Interest received, classified as investing activities |
3,900,000
GBP
|
— | — | — | — |
1,900,000
GBP
|
— | — | — |
| Other inflows (outflows) of cash, classified as investing activities |
900,000
GBP
|
— | — | — | — |
1,600,000
GBP
|
— | — | — |
| Cash flows from (used in) investing activities |
5,400,000
GBP
|
— | — | — | — |
35,300,000
GBP
|
— | — | — |
| Cash flows from (used in) financing activities [abstract] | |||||||||
| Payments to acquire or redeem entity's shares |
88,800,000
GBP
|
— | — | — | — |
91,200,000
GBP
|
— | — | — |
| Proceeds from borrowings, classified as financing activities |
—
GBP
|
— | — | — | — |
205,000,000
GBP
|
— | — | — |
| Repayments of borrowings, classified as financing activities |
44,500,000
GBP
|
— | — | — | — |
354,300,000
GBP
|
— | — | — |
| Payments of lease liabilities, classified as financing activities |
124,400,000
GBP
|
— | — | — | — |
120,500,000
GBP
|
— | — | — |
| Interest paid, classified as financing activities |
30,400,000
GBP
|
— | — | — | — |
24,400,000
GBP
|
— | — | — |
| Cash flows from (used in) financing activities |
347,900,000
GBP
|
— | — | — | — |
436,800,000
GBP
|
— | — | — |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes |
39,800,000
GBP
|
— | — | — | — |
144,900,000
GBP
|
— | — | — |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||||||
| Effect of exchange rate changes on cash and cash equivalents |
2,600,000
GBP
|
— | — | — | — |
3,700,000
GBP
|
— | — | — |
| Cash and cash equivalents | — |
94,400,000
GBP
|
— | — |
57,200,000
GBP
|
— | — | — |
198,400,000
GBP
|