CHRIS, the relevant legislation is now SI 2020/1103, The Health Protection (Coronavirus, Local COVID-19 Alert Level) (Medium) (England) Regulations 2020 as that is the SI dealing with Tier 1.
That SI also revoked Regulation 5 in the SI you quoted, relating to the limit of six folk.
The limit is six still as Schedule 1of SI 2020/1103 states,
"Participation in gatherings
1.—(1) No person may participate in a gathering in the Tier 1 area which consists of more than six people.
(2) Sub-paragraph (1) does not apply if any of the exceptions set out in paragraph 3 apply.
(3) This paragraph does not permit a person to participate in a gathering in the Tier 1 area in contravention of—
(a)paragraph 1(2) or 2(2) of Schedule 1 to the Health Protection (Coronavirus, Local COVID-19 Alert Level) (High) (England) Regulations 2020, or
(b)paragraph 1(2) or 2(2) of Schedule 1 to the Health Protection (Coronavirus, Local COVID-19 Alert Level) (Very High) (England) Regulations 2020."
With all the amendments, it must be a full-time job keeping up-to-date and ensuring all the interested parties are kept informed.