Statement Of Cash Flows [Abstract]
| Concept |
As at 2023-03-31 |
2022-04-01 to 2023-03-31 |
2022-04-01 to 2023-03-31 |
2022-04-01 to 2023-03-31 |
2021-04-01 to 2022-03-31 |
2021-04-01 to 2022-03-31 |
2021-04-01 to 2022-03-31 |
As at 2022-03-31 |
As at 2021-03-31 |
|---|---|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||||||
| Cash flows from (used in) operating activities [abstract] | |||||||||
| Profit (loss) | — |
4,064,000,000
GBP
|
509,000,000
GBP
|
4,573,000,000
GBP
|
3,547,000,000
GBP
|
466,000,000
GBP
|
4,013,000,000
GBP
|
— | — |
| Interest received, classified as operating activities | — | — | — |
4,000,000
GBP
|
— | — |
–
GBP
|
— | — |
| Income taxes paid (refund), classified as operating activities | — | — | — |
–
GBP
|
— | — |
1,000,000
GBP
|
— | — |
| Cash flows from (used in) operating activities | — | — | — |
727,000,000
GBP
|
— | — |
490,000,000
GBP
|
— | — |
| Cash flows from (used in) investing activities [abstract] | |||||||||
| Purchase of property, plant and equipment, classified as investing activities | — | — | — |
1,000,000
GBP
|
— | — |
–
GBP
|
— | — |
| Cash flows from (used in) investing activities | — | — | — |
1,000,000
GBP
|
— | — |
–
GBP
|
— | — |
| Cash flows from (used in) financing activities [abstract] | |||||||||
| Proceeds from issuing shares | — | — | — |
1,000,000
GBP
|
— | — |
1,000,000
GBP
|
— | — |
| Payments to acquire or redeem entity's shares | — | — | — |
30,000,000
GBP
|
— | — |
54,000,000
GBP
|
— | — |
| Repayments of borrowings, classified as financing activities | — | — | — |
200,000,000
GBP
|
— | — |
–
GBP
|
— | — |
| Payments of lease liabilities, classified as financing activities | — | — | — |
5,000,000
GBP
|
— | — |
4,000,000
GBP
|
— | — |
| Dividends paid, classified as financing activities | — | — | — |
485,000,000
GBP
|
— | — |
389,000,000
GBP
|
— | — |
| Interest paid, classified as financing activities | — | — | — |
54,000,000
GBP
|
— | — |
52,000,000
GBP
|
— | — |
| Cash flows from (used in) financing activities | — | — | — |
773,000,000
GBP
|
— | — |
498,000,000
GBP
|
— | — |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — | — | — |
47,000,000
GBP
|
— | — |
8,000,000
GBP
|
— | — |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||||||
| Effect of exchange rate changes on cash and cash equivalents | — | — | — |
3,000,000
GBP
|
— | — |
4,000,000
GBP
|
— | — |
| Cash and cash equivalents |
162,000,000
GBP
|
— | — | — | — | — | — |
212,000,000
GBP
|
216,000,000
GBP
|