Property, plant and equipment (Details) - GBP (£) £ in Millions	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Disclosure of property, plant and equipment [text block] [Abstract]
Acquired property, plant and equipment cost	£ 51.0	£ 8.2
Recognised property, plant and equipment on acquisition	£ 56.1

The increase in property, plant and equipment resulting from acquisitions through business combinations. [Refer: Business combinations [member]; Property, plant and equipment]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2021-01-01
-Paragraph 73
-Subparagraph e
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=16&code=ifrs-tx-2021-en-r&anchor=para_73_e_iii&doctype=Standard
-URIDate 2021-03-24

Name:	ifrs-full_AcquisitionsThroughBusinessCombinationsPropertyPlantAndEquipment
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration