Analysis Of Income And Expense [Abstract]
| Concept |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Analysis of income and expense [abstract] | ||||||||||||
| Revenue [abstract] | ||||||||||||
| Revenue | — | — | — | — |
2,956,600,000
GBP
|
— | — |
2,803,300,000
GBP
|
— | — | — | — |
| Material income and expense [abstract] | ||||||||||||
| Operating expense | — | — | — | — |
2,610 . 1
GBP
|
— | — |
2,509,500,000
GBP
|
— | — | — | — |
| Expenses by nature [abstract] | ||||||||||||
| Classes of employee benefits expense [abstract] | ||||||||||||
| Expense from share-based payment transactions with employees | — | — | — | — |
9,800,000
GBP
|
9,800,000
GBP
|
5,500,000
GBP
|
5,500,000
GBP
|
— | — | — | — |
| Miscellaneous other comprehensive income [abstract] | ||||||||||||
| Other comprehensive income, net of tax, exchange differences on translation of foreign operations and hedges of net investments in foreign operations [abstract] | ||||||||||||
| Other comprehensive income, net of tax, exchange differences on translation of foreign operations | — | — | — |
17 . 7
GBP
|
17 . 7
GBP
|
— | — |
35,400,000
GBP
|
35,400,000
GBP
|
— | — | — |
| Other comprehensive income, before tax, exchange differences on translation of foreign operations and hedges of net investments in foreign operations [abstract] | ||||||||||||
| Other comprehensive income, before tax, exchange differences on translation of foreign operations | — | — | — | — |
17 . 7
GBP
|
— | — |
35,400,000
GBP
|
— | — | — | — |
| Other comprehensive income, before tax, hedges of net investments in foreign operations | — | — | — | — |
15,000,000
GBP
|
— | — |
17 .2
GBP
|
— | — | — | — |
| Share of profit (loss) of associates and joint ventures accounted for using equity method [abstract] | ||||||||||||
| Share of profit (loss) of associates and joint ventures accounted for using equity method | — | — | — | — |
8 .1
GBP
|
— | — |
8,300,000
GBP
|
— | — | — | — |
| Income tax relating to components of other comprehensive income [abstract] | ||||||||||||
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss | — | — | — | — |
2,000,000
GBP
|
2,000,000
GBP
|
3,900,000
GBP
|
3,900,000
GBP
|
— | — | — | — |
| Income tax relating to components of other comprehensive income that will be reclassified to profit or loss | — | — | — | — |
4 .6
GBP
|
4,600,000
GBP
|
3,200,000
GBP
|
3,200,000
GBP
|
— | — | — | — |
| Income tax relating to components of other comprehensive income | — | — | — | — |
2,000,000
GBP
|
— | — |
3,900,000
GBP
|
— | — | — | — |
| Comprehensive income, continuing and discontinued operations [abstract] | ||||||||||||
| Comprehensive income |
1,500,000
GBP
|
13,200,000
GBP
|
10,400,000
GBP
|
2. 7
GBP
|
275. 1
GBP
|
276,500,000
GBP
|
176. 7
GBP
|
118,600,000
GBP
|
52,600,000
GBP
|
0. 4
GBP
|
4,900,000
GBP
|
1,000,000
GBP
|