<ul><li><a href=http://www.legislation.gov.uk/ukpga/2003/21/contents target=_blank>Communications Act(Communications Act 2003, last updated in December 2017, s. 88)</a></li><li><a href=https://www.ofcom.org.uk/__data/assets/pdf_file/0020/112475/wla-statement-vol-1.pdf target=_blank>Wholesale Local Access Market Review: Statement – Volume 1(Ofcom document explicitly states a reference offer requirement (see for example point 6.116 on page 121, explicit reference to VULA, an active service, and reference offer requirement)</a></li></ul>