v3.25.4
Other Comprehensive Income - Schedule of Other Comprehensive Income (Detail) - GBP (£)
£ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Items that may be reclassified to the income statement      
Net exchange differences on translation of foreign operations £ (193) £ (35) £ (177)
Currency translation adjustment disposed 0 0 (122)
Attributable tax 0 2 0
Items that are not reclassified to the income statement      
Fair value losses on other financial assets (7) (2) 1
Attributable tax 0 0 0
Remeasurement of retirement benefit obligations 10 5 (85)
Attributable tax (3) (2) 20
Other comprehensive expense for the year (193) (32) (363)
Fair value reserve [member]      
Items that may be reclassified to the income statement      
Net exchange differences on translation of foreign operations 0 0 0
Currency translation adjustment disposed 0 0 0
Attributable tax 0 0 0
Items that are not reclassified to the income statement      
Fair value losses on other financial assets (7) (2) 1
Attributable tax 0 0 0
Remeasurement of retirement benefit obligations 0 0 0
Attributable tax 0 0 0
Other comprehensive expense for the year (7) (2) 1
Translation reserve [member]      
Items that may be reclassified to the income statement      
Net exchange differences on translation of foreign operations (192) (35) (176)
Currency translation adjustment disposed 0 0 (122)
Attributable tax 0 0 0
Items that are not reclassified to the income statement      
Fair value losses on other financial assets 0 0 0
Attributable tax 0 0 0
Remeasurement of retirement benefit obligations 0 0 0
Attributable tax 0 0 0
Other comprehensive expense for the year (192) (35) (298)
Retained earnings [member]      
Items that may be reclassified to the income statement      
Net exchange differences on translation of foreign operations 0 0 0
Currency translation adjustment disposed 0 0 0
Attributable tax 0 2 0
Items that are not reclassified to the income statement      
Fair value losses on other financial assets 0 0 0
Attributable tax 0 0 0
Remeasurement of retirement benefit obligations 10 5 (85)
Attributable tax (3) (2) 20
Other comprehensive expense for the year 7 5 (65)
Equity attributable to equity holders of the company [member]      
Items that may be reclassified to the income statement      
Net exchange differences on translation of foreign operations (192) (35) (176)
Currency translation adjustment disposed 0 0 (122)
Attributable tax 0 2 0
Items that are not reclassified to the income statement      
Fair value losses on other financial assets (7) (2) 1
Attributable tax 0 0 0
Remeasurement of retirement benefit obligations 10 5 (85)
Attributable tax (3) (2) 20
Other comprehensive expense for the year (192) (32) (362)
Non-controlling interest [member]      
Items that may be reclassified to the income statement      
Net exchange differences on translation of foreign operations (1) 0 (1)
Currency translation adjustment disposed 0 0 0
Attributable tax 0 0 0
Items that are not reclassified to the income statement      
Fair value losses on other financial assets 0 0 0
Attributable tax 0 0 0
Remeasurement of retirement benefit obligations 0 0 0
Attributable tax 0 0 0
Other comprehensive expense for the year £ (1) £ 0 £ (1)