Interests in associates, joint ventures and other investments - Movements in Associates, Joint Ventures and Other Investments (Details) - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Movements in interests in associates and joint ventures
Beginning balance	£ 305.1	£ 412.9
Additions	39.4	4.4
Loss from associates - after interest and tax	25.1	(60.4)
Share of other comprehensive income of associate undertakings	(0.9)	51.2	£ 13.5
Dividends	(30.4)	(37.6)
Other movements	(12.5)	2.9
Exchange adjustments	(19.3)	17.1
Disposals	(5.4)	(9.6)
Reclassification from subsidiaries		(5.9)
Reclassification from associates to other investments		(22.5)
Amortisation of other intangible assets		(0.2)
Impairment charges	(14.6)	(47.2)
Ending balance	286.5	305.1	412.9
Movements in interests in other investments
Beginning balance	369.8	318.3
Additions	2.5	5.1
Disposals	(10.4)	(16.0)
Reclassification from associates to other investments		61.6
Revaluation of other investments through profit or loss	(26.2)	23.1
Revaluation of other investments through other comprehensive income	(3.0)	(22.3)
Ending balance	£ 332.7	£ 369.8	£ 318.3

The amount of investments accounted for using the equity method. The equity method is a method of accounting whereby the investment is initially recognised at cost and adjusted thereafter for the post-acquisition change in the investor's share of net assets of the investee. The investor's profit or loss includes its share of the profit or loss of the investee. The investor's other comprehensive income includes its share of the other comprehensive income of the investee. [Refer: At cost [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 24
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_24_a&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph B16
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_B16&doctype=Appendix&subtype=B
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 54
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_54_e&doctype=Standard
-URIDate 2023-03-23