score:5
Refer UK Immigration Rules, Appendix V, Part 4. Specifically sections 4.2, 4.5 and 4.7.
Section 4.2 (a) & (b) - The applicant must satisfy the decision maker that they are a genuine visitor...(a) will leave the UK at the end of their visit; and (b) will not live in the UK for extended periods through frequent or successive visits, or make the UK their main home; and
Section 4.5 (f) - "The applicant must not intend to work in the UK, which includes the following...(f)providing goods and services"
Section 4.7 - "The applicant must not receive payment from a UK source for any activities undertaken in the UK".
Interpret them as you will but as 4.5 and 4.7 are somewhat contradictory, this question can't be answered conclusively except by a UK Immigration Officer.
Other members, who may appear to comment or Answer, indicate 4.7 is what would lead to a Yes answer for this question.
Note: These are admissibility rules, taxes are a completely different subject.