Statement Of Comprehensive Income [Abstract]
| Concept |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | ||||||||||||
| Profit (loss) |
—
GBP
|
—
GBP
|
2 55.4
GBP
|
—
GBP
|
2 55.4
GBP
|
—
GBP
|
—
GBP
|
56 1 .0
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
56 1.0
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 | — | — |
35,100,000
GBP
|
— | — | — | — |
5,200,000
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 | — | — |
9,800,000
GBP
|
— | — | — | — |
7 .6
GBP
|
— | — | — | — |
| Other comprehensive income |
—
GBP
|
—
GBP
|
25,300,000
GBP
|
—
GBP
|
25,300,000
GBP
|
—
GBP
|
—
GBP
|
2,400,000
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
2,400,000
GBP
|
| Comprehensive income | — | — |
230,100,000
GBP
|
— | — | — | — |
558,600,000
GBP
|
— | — | — | — |