Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
|---|---|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||||
| Property, plant and equipment [abstract] | ||||||
| Property, plant and equipment |
54,000,000
GBP
|
22,600,000
GBP
|
23,700,000
GBP
|
50,200,000
GBP
|
— | — |
| Investment property [abstract] | ||||||
| Investment property |
5,359,900,000
GBP
|
–
GBP
|
–
GBP
|
5,029,100,000
GBP
|
— | — |
| Investments accounted for using equity method [abstract] | ||||||
| Investments accounted for using equity method |
51,100,000
GBP
|
1,749,800,000
GBP
|
1,615,900,000
GBP
|
900,000
GBP
|
— | — |
| Trade and other non-current receivables [abstract] | ||||||
| Other non-current receivables |
159,300,000
GBP
|
–
GBP
|
–
GBP
|
146,400,000
GBP
|
— | — |
| Miscellaneous non-current assets [abstract] | ||||||
| Non-current net defined benefit asset |
1,800,000
GBP
|
1,800,000
GBP
|
–
GBP
|
–
GBP
|
— | — |
| Trade and other current receivables [abstract] | ||||||
| Trade and other current receivables |
61,700,000
GBP
|
1,898,900,000
GBP
|
1,682,300,000
GBP
|
76,200,000
GBP
|
— | — |
| Cash and cash equivalents [abstract] | ||||||
| Cash and cash equivalents |
68,500,000
GBP
|
68,200,000
GBP
|
50,100,000
GBP
|
50,700,000
GBP
|
54,000,000
GBP
|
54,500,000
GBP
|
| Non-current assets or disposal groups classified as held for sale or as held for distribution to owners [abstract] | ||||||
| Non-current assets or disposal groups classified as held for sale |
102,800,000
GBP
|
–
GBP
|
–
GBP
|
165,000,000
GBP
|
— | — |
| Borrowings [abstract] | ||||||
| Non-current portion of non-current borrowings |
1,237,100,000
GBP
|
1,054,700,000
GBP
|
821,700,000
GBP
|
1,033,200,000
GBP
|
— | — |
| Current borrowings and current portion of non-current borrowings [abstract] | ||||||
| Current borrowings |
12,300,000
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
— | — |
| Non-current portion of non-current borrowings, by type [abstract] | ||||||
| Trade and other current payables [abstract] | ||||||
| Trade and other current payables |
128,300,000
GBP
|
1,281,700,000
GBP
|
1,072,900,000
GBP
|
106,700,000
GBP
|
— | — |
| Miscellaneous non-current liabilities [abstract] | ||||||
| Non-current net defined benefit liability |
–
GBP
|
–
GBP
|
2,200,000
GBP
|
2,200,000
GBP
|
— | — |
| Non-current derivative financial liabilities |
400,000
GBP
|
400,000
GBP
|
5,600,000
GBP
|
5,600,000
GBP
|
— | — |
| Miscellaneous current liabilities [abstract] | ||||||
| Current derivative financial liabilities |
400,000
GBP
|
400,000
GBP
|
–
GBP
|
–
GBP
|
— | — |
| Issued capital [abstract] | ||||||
| Issued capital |
5,600,000
GBP
|
5,600,000
GBP
|
5,600,000
GBP
|
5,600,000
GBP
|
— | — |
| Retained earnings [abstract] | ||||||
| Retained earnings |
3,299,700,000
GBP
|
255,700,000
GBP
|
321,200,000
GBP
|
3,124,500,000
GBP
|
— | — |
| Net assets (liabilities) [abstract] | ||||||
| Assets |
5,892,000,000
GBP
|
3,744,900,000
GBP
|
3,375,500,000
GBP
|
5,531,400,000
GBP
|
— | — |
| Liabilities |
1,450,200,000
GBP
|
2,362,600,000
GBP
|
1,928,700,000
GBP
|
1,216,300,000
GBP
|
— | — |
| Assets (liabilities) |
4,441,800,000
GBP
|
1,382,300,000
GBP
|
1,446,800,000
GBP
|
4,315,100,000
GBP
|
— | — |
| Net current assets (liabilities) [abstract] | ||||||
| Current assets |
162,800,000
GBP
|
1,967,100,000
GBP
|
1,732,800,000
GBP
|
139,800,000
GBP
|
— | — |
| Current liabilities |
193,000,000
GBP
|
1,284,300,000
GBP
|
1,074,700,000
GBP
|
107,800,000
GBP
|
— | — |
| Assets less current liabilities [abstract] |