Statement Of Financial Position [Abstract]
| Concept |
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 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||
| Property, plant and equipment | — | — | — | — | — |
100,000
GBP
|
400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Non-current assets | — | — | — | — | — |
1,302,600,000
GBP
|
1,287,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current assets [abstract] | ||||||||||||||||||
| Trade and other current receivables | — | — | — | — | — |
1,600,000
GBP
|
5,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — | — | — |
57,000,000
GBP
|
22,900,000
GBP
|
— | — | — | — | — | — | — | — | — |
78,100,000
GBP
|
— |
| Current assets | — | — | — | — | — |
58,600,000
GBP
|
27,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital | — | — | — | — | — |
1,900,000
GBP
|
1,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Retained earnings | — | — | — | — | — |
511,700,000
GBP
|
552,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Share premium | — | — | — | — | — |
671,200,000
GBP
|
615,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Treasury shares | — | — | — | — | — |
8,800,000
GBP
|
8,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Other reserves | — | — | — | — | — |
74,700,000
GBP
|
33,300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Equity |
74,700,000
GBP
|
511,700,000
GBP
|
671,200,000
GBP
|
1,900,000
GBP
|
8,800,000
GBP
|
1,250,700,000
GBP
|
1,194,100,000
GBP
|
615,900,000
GBP
|
1,500,000
GBP
|
8,900,000
GBP
|
552,300,000
GBP
|
33,300,000
GBP
|
8,200,000
GBP
|
1,500,000
GBP
|
795,700,000
GBP
|
615,900,000
GBP
|
1,433,800,000
GBP
|
28,900,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||
| Non-current provisions | — | — | — | — | — |
300,000
GBP
|
300,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Deferred tax liabilities | — | — | — | — | — |
11,700,000
GBP
|
22,500,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Non-current liabilities | — | — | — | — | — |
101,400,000
GBP
|
111,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current liabilities [abstract] | ||||||||||||||||||
| Trade and other current payables | — | — | — | — | — |
9,100,000
GBP
|
9,600,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Current liabilities | — | — | — | — | — |
9,100,000
GBP
|
9,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |