The 'The Work at Height (Amendment) Regulations 2007' amended the Work at Height Regulation 2005. I don't believe the amendment has been repealed (could be wrong though)?
amendment:
https://www.legislation.gov.uk/uksi/2007/114/made
full regulations:
https://www.legislation.gov.uk/uksi/2005/735/regulation/14A
"Special provision in relation to caving and climbing
14A.—(1) Paragraph (2) applies in relation to the application of these Regulations to work concerning the provision of instruction or leadership to one or more persons in connection with their engagement in caving or climbing by way of sport, recreation, team building or similar activities.
(2) Where this paragraph applies, an employer, self-employed person or other person shall be taken to have complied with the caving and climbing requirements, if, by alternative means to any requirement of those requirements, he maintains in relation to a person at such work as is referred to in paragraph (1) a level of safety equivalent to that required by those requirements.
(3) For the purposes of paragraph (2), in determining whether an equivalent level of safety is maintained, regard shall be had to —
(a)the nature of the activity;
(b)any publicly available and generally accepted procedures for the activity; and
(c)any other relevant circumstances.
(4) In this regulation —
(a)“caving” includes the exploration of parts of mines which are no longer worked;
(b)“climbing” means climbing, traversing, abseiling or scrambling over natural terrain or man-made structures; and
(c)“the caving and climbing requirements” means regulation 8(d)(ii), so far as it relates to paragraph 1 in Part 3 of Schedule 5, and that paragraph."