Statement Of Financial Position [Abstract]
| Concept |
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 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2022-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
As at 2021-03-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||||||
| Assets [abstract] | |||||||||||||||||||||
| Property, plant and equipment | — |
186,300,000
GBP
|
— | — | — | — | — | — | — | — |
177,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Right-of-use assets | — |
46,900,000
GBP
|
— | — | — | — | — | — | — | — |
45,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Current tax assets | — |
19,900,000
GBP
|
— | — | — | — | — | — | — | — |
11,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Deferred tax assets | — |
6,900,000
GBP
|
— | — | — | — | — | — | — | — |
4,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — |
120,500,000
GBP
|
— | — | — | — | — | — | — | — |
158,400,000
GBP
|
— | — | — | — | — | — |
86,400,000
GBP
|
— | — | — |
| Assets | — |
2,544,000,000
GBP
|
— | — | — | — | — | — | — | — |
2,101,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | |||||||||||||||||||||
| Equity [abstract] | |||||||||||||||||||||
| Retained earnings | — |
954,300,000
GBP
|
— | — | — | — | — | — | — | — |
772,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Treasury shares | — |
2,200,000
GBP
|
— | — | — | — | — | — | — | — |
3,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Other reserves | — |
108,800,000
GBP
|
— | — | — | — | — | — | — | — |
60,200,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent | — |
1,344,200,000
GBP
|
— | — | — | — | — | — | — | — |
1,108,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Non-controlling interests | — |
700,000
GBP
|
— | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Equity |
1,344,200,000
GBP
|
1,344,900,000
GBP
|
2,200,000
GBP
|
700,000
GBP
|
954,300,000
GBP
|
283,300,000
GBP
|
108,800,000
GBP
|
3,000,000
GBP
|
1,108,500,000
GBP
|
772,800,000
GBP
|
1,108,500,000
GBP
|
–
GBP
|
278,500,000
GBP
|
60,200,000
GBP
|
1,500,000
GBP
|
587,800,000
GBP
|
37,600,000
GBP
|
899,400,000
GBP
|
275,500,000
GBP
|
–
GBP
|
899,400,000
GBP
|
| Liabilities [abstract] | |||||||||||||||||||||
| Current tax liabilities | — |
22,100,000
GBP
|
— | — | — | — | — | — | — | — |
19,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — |
90,100,000
GBP
|
— | — | — | — | — | — | — | — |
60,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
| Liabilities | — |
1,199,100,000
GBP
|
— | — | — | — | — | — | — | — |
992,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — |