Statement Of Financial Position [Abstract]
| Concept |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2025-03-30 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2024-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
As at 2023-03-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||||||||
| Property, plant and equipment | — |
49,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
59,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Right-of-use assets | — |
143,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
173,500,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Deferred tax assets | — |
11,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
11,200,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Non-current assets | — |
478,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
515,200,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||||||||
| Current inventories | — |
187 .4
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
254,600,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Trade and other current receivables | — |
62,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
68,800,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — |
155,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
111,100,000
GBP
|
— | — |
157 .5
GBP
|
— | — | — | — | — | — |
| Current assets | — |
410,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
437 .2
GBP
|
— | — | — | — | — | — | — | — | — |
| Assets | — |
889,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
952,400,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||||||||
| Issued capital | — |
9,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
9,600,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Retained earnings | — |
1,749,100,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
1,747 .6
GBP
|
— | — | — | — | — | — | — | — | — |
| Treasury shares | — |
–
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — |
| Equity |
1,749,100,000
GBP
|
366,400,000
GBP
|
9,600,000
GBP
|
700,000
GBP
|
–
GBP
|
1,400,000,000
GBP
|
400,000
GBP
|
6,600,000
GBP
|
1,400,000,000
GBP
|
900,000
GBP
|
1,747 .6
GBP
|
9,600,000
GBP
|
–
GBP
|
400,000
GBP
|
368,200,000
GBP
|
9,700,000
GBP
|
500,000
GBP
|
404,200,000
GBP
|
10,000,000
GBP
|
–
GBP
|
–
GBP
|
1,782,200,000
GBP
|
1,400,000,000
GBP
|
12,500,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||||||||
| Non-current provisions | — |
6,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
6,300,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — |
2,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
2,800,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Non-current liabilities | — |
364,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
430,700,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||||||||
| Trade and other current payables | — |
108,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
92,200,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Current liabilities | — |
158,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
153,500,000
GBP
|
— | — | — | — | — | — | — | — | — |
| Liabilities | — |
523,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
584,200,000
GBP
|
— | — | — | — | — | — | — | — | — |