Statement Of Changes In Equity [Abstract]
| Concept |
As at 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 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
2022-01-01 to 2022-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | ||||||||||||||||||||||||||||||||||
| Statement of changes in equity [line items] | ||||||||||||||||||||||||||||||||||
| Equity |
413,200,000
GBP
|
— | — | — | — | — | — | — |
114,800,000
GBP
|
3,500,000
GBP
|
287 .2
GBP
|
7. 7
GBP
|
409,700,000
GBP
|
— | — | — | — |
245,300,000
GBP
|
104,000,000
GBP
|
— | — |
361,600,000
GBP
|
356,900,000
GBP
|
4,700,000
GBP
|
— |
7. 6
GBP
|
— | — |
211,900,000
GBP
|
4,300,000
GBP
|
32 4. 1
GBP
|
7. 6
GBP
|
104,600,000
GBP
|
328,400,000
GBP
|
| Changes in equity [abstract] | ||||||||||||||||||||||||||||||||||
| Comprehensive income [abstract] | ||||||||||||||||||||||||||||||||||
| Profit (loss) | — |
–
GBP
|
–
GBP
|
79. 6
GBP
|
75,600,000
GBP
|
4 .0
GBP
|
700,000
GBP
|
80,300,000
GBP
|
— | — | — | — | — |
7 5.6
GBP
|
54,700,000
GBP
|
300,000
GBP
|
4,300,000
GBP
|
— | — |
–
GBP
|
5 0 .1
GBP
|
— | — | — |
–
GBP
|
— |
54,400,000
GBP
|
5 0 .1
GBP
|
— | — | — | — | — | — |
| Other comprehensive income | — |
–
GBP
|
7. 9
GBP
|
2,400,000
GBP
|
5,500,000
GBP
|
–
GBP
|
— | — | — | — | — | — | — |
2,400,000
GBP
|
— | — |
–
GBP
|
— | — |
2,700,000
GBP
|
2,800,000
GBP
|
— | — | — |
–
GBP
|
— |
2,800,000
GBP
|
5,500,000
GBP
|
— | — | — | — | — | — |
| Comprehensive income | — |
–
GBP
|
7. 9
GBP
|
82,000,000
GBP
|
70,100,000
GBP
|
4 .0
GBP
|
— | — | — | — | — | — | — |
7 8.0
GBP
|
— | — |
4,300,000
GBP
|
— | — |
2,700,000
GBP
|
52,900,000
GBP
|
— | — | — |
–
GBP
|
— |
5 7. 2
GBP
|
55,600,000
GBP
|
— | — | — | — | — | — |
| Issue of equity | — |
0 .1
GBP
|
2,600,000
GBP
|
2 .7
GBP
|
–
GBP
|
–
GBP
|
— | — | — | — | — | — | — |
2 .7
GBP
|
— | — |
–
GBP
|
— | — |
1,800,000
GBP
|
1,800,000
GBP
|
— | — | — |
–
GBP
|
— |
1,800,000
GBP
|
–
GBP
|
— | — | — | — | — | — |
| Dividends recognised as distributions to owners | — |
–
GBP
|
–
GBP
|
30,200,000
GBP
|
25,900,000
GBP
|
4,300,000
GBP
|
— | — | — | — | — | — | — |
25,900,000
GBP
|
— | — |
3,900,000
GBP
|
— | — |
–
GBP
|
24,400,000
GBP
|
— | — | — |
–
GBP
|
— |
28,300,000
GBP
|
24,400,000
GBP
|
— | — | — | — | — | — |
| Increase (decrease) through share-based payment transactions, equity | — |
–
GBP
|
0. 3
GBP
|
1,000,000
GBP
|
1,300,000
GBP
|
–
GBP
|
— | — | — | — | — | — | — |
1,000,000
GBP
|
— | — |
–
GBP
|
— | — |
300,000
GBP
|
0. 2
GBP
|
— | — | — |
–
GBP
|
— |
200,000
GBP
|
0. 1
GBP
|
— | — | — | — | — | — |