Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2021-12-31 |
As at 2020-12-31 |
As at 2020-01-01 |
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment |
66,600,000
GBP
|
65,800,000
GBP
|
79,500,000
GBP
|
| Investment property [abstract] | |||
| Investment property |
800,000
GBP
|
2,700,000
GBP
|
5,100,000
GBP
|
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in joint ventures reported in separate financial statements |
94,100,000
GBP
|
91,400,000
GBP
|
84,300,000
GBP
|
| Miscellaneous non-current assets [abstract] | |||
| Non-current investments other than investments accounted for using equity method |
–
GBP
|
–
GBP
|
1,300,000
GBP
|
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables |
328,300,000
GBP
|
234,600,000
GBP
|
275,700,000
GBP
|
| Current prepayments and current accrued income including current contract assets [abstract] | |||
| Current accrued income including current contract assets [abstract] | |||
| Current contract assets |
232,600,000
GBP
|
171,800,000
GBP
|
186,800,000
GBP
|
| Categories of non-current financial assets [abstract] | |||
| Non-current loans and receivables |
–
GBP
|
5,500,000
GBP
|
8,400,000
GBP
|
| Categories of current financial assets [abstract] | |||
| Current loans and receivables |
1,500,000
GBP
|
–
GBP
|
–
GBP
|
| Classes of current inventories [abstract] | |||
| Current inventories |
288,500,000
GBP
|
294,200,000
GBP
|
338,100,000
GBP
|
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents |
468,600,000
GBP
|
400,500,000
GBP
|
251,200,000
GBP
|
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings |
400,000
GBP
|
400,000
GBP
|
–
GBP
|
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings |
110,200,000
GBP
|
67,300,000
GBP
|
58,500,000
GBP
|
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Trade and other non-current payables |
32,600,000
GBP
|
1,700,000
GBP
|
3,800,000
GBP
|
| Trade and other current payables [abstract] | |||
| Current accruals and current deferred income including current contract liabilities [abstract] | |||
| Current deferred income including current contract liabilities [abstract] | |||
| Current contract liabilities [abstract] | |||
| Current contract liabilities |
78,500,000
GBP
|
55,600,000
GBP
|
56,200,000
GBP
|
| Trade and other current payables |
891,400,000
GBP
|
847,900,000
GBP
|
842,300,000
GBP
|
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability |
200,000
GBP
|
200,000
GBP
|
–
GBP
|
| Issued capital [abstract] | |||
| Issued capital |
2,300,000
GBP
|
2,300,000
GBP
|
2,300,000
GBP
|
| Retained earnings [abstract] | |||
| Retained earnings |
427,100,000
GBP
|
373,100,000
GBP
|
346,900,000
GBP
|
| Accumulated other comprehensive income [abstract] | |||
| Reserve of exchange differences on translation |
800,000
GBP
|
800,000
GBP
|
— |
| Reserve of cash flow hedges |
800,000
GBP
|
600,000
GBP
|
— |
| Miscellaneous equity [abstract] | |||
| Capital redemption reserve |
600,000
GBP
|
600,000
GBP
|
— |
| Net assets (liabilities) [abstract] | |||
| Assets |
1,707,600,000
GBP
|
1,488,600,000
GBP
|
1,454,000,000
GBP
|
| Liabilities |
1,233,400,000
GBP
|
1,068,500,000
GBP
|
1,067,100,000
GBP
|
| Assets (liabilities) |
474,200,000
GBP
|
420,100,000
GBP
|
386,900,000
GBP
|
| Net current assets (liabilities) [abstract] | |||
| Current assets |
1,324,200,000
GBP
|
1,101,100,000
GBP
|
1,051,800,000
GBP
|
| Current liabilities |
1,126,900,000
GBP
|
988,800,000
GBP
|
986,500,000
GBP
|
| Current assets (liabilities) |
197,300,000
GBP
|
112,300,000
GBP
|
65,300,000
GBP
|
| Assets less current liabilities [abstract] |