Statement Of Comprehensive Income [Abstract]
| Concept |
2024-04-01 to 2025-03-31 |
2024-04-01 to 2025-03-31 |
2024-04-01 to 2025-03-31 |
2024-04-01 to 2025-03-31 |
2024-04-01 to 2025-03-31 |
2023-04-01 to 2024-03-31 |
2023-04-01 to 2024-03-31 |
2023-04-01 to 2024-03-31 |
2023-04-01 to 2024-03-31 |
2023-04-01 to 2024-03-31 |
|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | ||||||||||
| Profit (loss) |
–
GBP
|
–
GBP
|
264,700,000
GBP
|
–
GBP
|
264,700,000
GBP
|
–
GBP
|
126,900,000
GBP
|
126,900,000
GBP
|
–
GBP
|
–
GBP
|
| Other comprehensive income [abstract] | ||||||||||
| Components of other comprehensive income that will not be reclassified to profit or loss, before tax [abstract] | ||||||||||
| Other comprehensive income, before tax, gains (losses) on remeasurements of defined benefit plans |
–
GBP
|
–
GBP
|
18,600,000
GBP
|
–
GBP
|
18,600,000
GBP
|
–
GBP
|
368,500,000
GBP
|
368,500,000
GBP
|
–
GBP
|
–
GBP
|
| Other comprehensive income, before tax, change in fair value of financial liability attributable to change in credit risk of liability |
–
GBP
|
–
GBP
|
1,900,000
GBP
|
–
GBP
|
1,900,000
GBP
|
–
GBP
|
700,000
GBP
|
700,000
GBP
|
–
GBP
|
–
GBP
|
| Components of other comprehensive income that will be reclassified to profit or loss, before tax [abstract] | ||||||||||
| Cash flow hedges [abstract] | ||||||||||
| Gains (losses) on cash flow hedges, before tax |
–
GBP
|
–
GBP
|
8,600,000
GBP
|
8,600,000
GBP
|
–
GBP
|
63,000,000
GBP
|
–
GBP
|
63,000,000
GBP
|
–
GBP
|
–
GBP
|
| Cost of hedging [abstract] | ||||||||||
| Change in value of foreign currency basis spreads [abstract] | ||||||||||
| Other comprehensive income, before tax, change in value of foreign currency basis spreads |
–
GBP
|
–
GBP
|
3,600,000
GBP
|
3,600,000
GBP
|
–
GBP
|
4,800,000
GBP
|
–
GBP
|
4,800,000
GBP
|
–
GBP
|
–
GBP
|
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss [abstract] | ||||||||||
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss | — | — |
6,000,000
GBP
|
— | — | — | — |
151,100,000
GBP
|
— | — |
| Income tax relating to components of other comprehensive income that will be reclassified to profit or loss [abstract] | ||||||||||
| Income tax relating to cash flow hedges included in other comprehensive income | — | — |
2,200,000
GBP
|
— | — | — | — |
15,800,000
GBP
|
— | — |
| Income tax relating to components of other comprehensive income that will be reclassified to profit or loss |
–
GBP
|
–
GBP
|
300,000
GBP
|
300,000
GBP
|
–
GBP
|
500,000
GBP
|
–
GBP
|
500,000
GBP
|
–
GBP
|
–
GBP
|
| Comprehensive income |
–
GBP
|
–
GBP
|
288,200,000
GBP
|
8,100,000
GBP
|
280,100,000
GBP
|
42,300,000
GBP
|
88,600,000
GBP
|
130,900,000
GBP
|
–
GBP
|
–
GBP
|