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 |
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 | — | — |
10,285,100,000
GBP
|
— | — |
10,111,100,000
GBP
|
— | — |
| Material income and expense [abstract] | ||||||||
| Finance income (cost) | — | — |
54,600,000
GBP
|
— | — |
62,800,000
GBP
|
— | — |
| Expenses by nature [abstract] | ||||||||
| Classes of employee benefits expense [abstract] | ||||||||
| Post-employment benefit expense in profit or loss [abstract] | ||||||||
| Post-employment benefit expense, defined contribution plans | — | — |
–
GBP
|
— | — |
16,800,000
GBP
|
— | — |
| Miscellaneous other comprehensive income [abstract] | ||||||||
| 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 | — |
89,800,000
GBP
|
89,800,000
GBP
|
— | — |
63,500,000
GBP
|
63,500,000
GBP
|
— |
| Other comprehensive income, before tax, hedges of net investments in foreign operations | — |
11,500,000
GBP
|
11,500,000
GBP
|
— | — |
15,900,000
GBP
|
15,900,000
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 | — | — |
19,300,000
GBP
|
— | — |
4,600,000
GBP
|
— | — |
| Income tax relating to components of other comprehensive income that will be reclassified to profit or loss | — | — |
–
GBP
|
— | — |
300,000
GBP
|
— | — |
| Income tax relating to components of other comprehensive income |
800,000
GBP
|
–
GBP
|
19,300,000
GBP
|
18,500,000
GBP
|
3,000,000
GBP
|
4,900,000
GBP
|
300,000
GBP
|
1,600,000
GBP
|
| Comprehensive income, continuing and discontinued operations [abstract] | ||||||||
| Comprehensive income |
3,600,000
GBP
|
78,300,000
GBP
|
423,700,000
GBP
|
498,400,000
GBP
|
416,800,000
GBP
|
330,800,000
GBP
|
79,100,000
GBP
|
6,900,000
GBP
|
| Comprehensive income attributable to owners of parent, continuing and discontinued operations [abstract] | ||||||||
| Comprehensive income, attributable to owners of parent | — | — |
423,700,000
GBP
|
— | — |
330,800,000
GBP
|
— | — |