Analysis Of Income And Expense [Abstract]

HEADLAM GROUP PLC - Filing #1587521

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	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	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	—	667,200,000 GBP	– GBP	—	—	—	—	—	667,200,000 GBP	—	578,100,000 GBP	—	—	578,100,000 GBP	– GBP	—	—	—	—	—
Material income and expense [abstract]
Finance income (cost)	—	1,500,000 GBP	– GBP	—	—	—	—	—	1,500,000 GBP	—	2,100,000 GBP	—	—	2,000,000 GBP	100,000 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	—	—	—	—	—	—	—	—	1,200,000 GBP	—	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	—	—	—	—	—	—	—	—	800,000 GBP	—	100,000 GBP	—	—	—	—	—	—	—	—	—
Comprehensive income, continuing and discontinued operations [abstract]
Comprehensive income	– GBP	—	—	– GBP	– GBP	– GBP	6,000,000 GBP	– GBP	16,600,000 GBP	22,600,000 GBP	19,600,000 GBP	– GBP	– GBP	—	—	20,500,000 GBP	– GBP	900,000 GBP	– GBP	– GBP
Comprehensive income attributable to owners of parent, continuing and discontinued operations [abstract]
Comprehensive income, attributable to owners of parent	—	—	—	—	—	—	—	—	16,600,000 GBP	—	19,600,000 GBP	—	—	—	—	—	—	—	—	—