Statement Of Cash Flows [Abstract]
| Concept |
2023-12-31 to 2024-12-28 |
2023-12-31 to 2024-12-28 |
2023-12-31 to 2024-12-28 |
As at 2024-12-28 |
2023-12-31 to 2024-12-28 |
2023-12-31 to 2024-12-28 |
2023-12-31 to 2024-12-28 |
2023-12-31 to 2024-12-28 |
2023-01-01 to 2023-12-30 |
2023-01-01 to 2023-12-30 |
2023-01-01 to 2023-12-30 |
2023-01-01 to 2023-12-30 |
2023-01-01 to 2023-12-30 |
2023-01-01 to 2023-12-30 |
As at 2023-12-30 |
2023-01-01 to 2023-12-30 |
As at 2022-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||||||||||||||
| Cash flows from (used in) operating activities [abstract] | |||||||||||||||||
| Profit (loss) |
–
GBP
|
–
GBP
|
153,400,000
GBP
|
— |
–
GBP
|
153,400,000
GBP
|
12,400,000
GBP
|
14 1.0
GBP
|
15,800,000
GBP
|
126,700,000
GBP
|
142,500,000
GBP
|
–
GBP
|
–
GBP
|
142,500,000
GBP
|
— |
–
GBP
|
— |
| Adjustments to reconcile profit (loss) [abstract] | |||||||||||||||||
| Adjustments for income tax expense | — | — |
50,500,000
GBP
|
— | — | — | — | — | — | — |
45,800,000
GBP
|
— | — | — | — | — | — |
| Adjustments for finance costs | — | — |
13,600,000
GBP
|
— | — | — | — | — | — | — |
10,100,000
GBP
|
— | — | — | — | — | — |
| Adjustments for decrease (increase) in inventories | — | — |
6,400,000
GBP
|
— | — | — | — | — | — | — |
8,200,000
GBP
|
— | — | — | — | — | — |
| Adjustments for provisions | — | — |
100,000
GBP
|
— | — | — | — | — | — | — |
500,000
GBP
|
— | — | — | — | — | — |
| Adjustments for share-based payments | — | — |
4,500,000
GBP
|
— | — | — | — | — | — | — |
4,600,000
GBP
|
— | — | — | — | — | — |
| Cash flows from (used in) operations | — | — |
352,600,000
GBP
|
— | — | — | — | — | — | — |
333,000,000
GBP
|
— | — | — | — | — | — |
| Income taxes paid (refund), classified as operating activities | — | — |
27 .7
GBP
|
— | — | — | — | — | — | — |
11,900,000
GBP
|
— | — | — | — | — | — |
| Cash flows from (used in) operating activities | — | — |
310,900,000
GBP
|
— | — | — | — | — | — | — |
3 10.8
GBP
|
— | — | — | — | — | — |
| Cash flows from (used in) investing activities [abstract] | |||||||||||||||||
| Proceeds from sales of property, plant and equipment, classified as investing activities | — | — |
16,100,000
GBP
|
— | — | — | — | — | — | — |
800,000
GBP
|
— | — | — | — | — | — |
| Purchase of property, plant and equipment, classified as investing activities | — | — |
230. 0
GBP
|
— | — | — | — | — | — | — |
189,500,000
GBP
|
— | — | — | — | — | — |
| Purchase of intangible assets, classified as investing activities | — | — |
10,900,000
GBP
|
— | — | — | — | — | — | — |
8,600,000
GBP
|
— | — | — | — | — | — |
| Interest received, classified as investing activities | — | — |
7. 7
GBP
|
— | — | — | — | — | — | — |
6,100,000
GBP
|
— | — | — | — | — | — |
| Cash flows from (used in) investing activities | — | — |
217 .1
GBP
|
— | — | — | — | — | — | — |
191,200,000
GBP
|
— | — | — | — | — | — |
| Cash flows from (used in) financing activities [abstract] | |||||||||||||||||
| Proceeds from issuing shares | — | — |
–
GBP
|
— | — | — | — | — | — | — |
2 .0
GBP
|
— | — | — | — | — | — |
| Payments to acquire or redeem entity's shares | — | — |
5,000,000
GBP
|
— | — | — | — | — | — | — |
5,000,000
GBP
|
— | — | — | — | — | — |
| Payments of lease liabilities, classified as financing activities | — | — |
56,700,000
GBP
|
— | — | — | — | — | — | — |
53,700,000
GBP
|
— | — | — | — | — | — |
| Dividends paid, classified as financing activities | — | — |
106,800,000
GBP
|
— | — | — | — | — | — | — |
60,800,000
GBP
|
— | — | — | — | — | — |
| Cash flows from (used in) financing activities | — | — |
163,800,000
GBP
|
— | — | — | — | — | — | — |
115,900,000
GBP
|
— | — | — | — | — | — |
| Increase (decrease) in cash and cash equivalents after effect of exchange rate changes | — | — |
70,000,000
GBP
|
— | — | — | — | — | — | — |
3,700,000
GBP
|
— | — | — | — | — | — |
| Cash and cash equivalents | — | — | — |
125,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
195,300,000
GBP
|
— |
191,600,000
GBP
|