LGA 1972 says:
Section 85 Vacation of office by failure to attend meetings.
(1)Subject to subsections (2) and (3) below, if a member of a local authority fails throughout a period of six consecutive months from the date of his last attendance to attend any meeting of the authority, he shall, unless the failure was due to some reason approved by the authority before the expiry of that period, cease to be a member of the authority.
(2)Attendance as a member at a meeting of any committee or sub-committee of the authority, or at a meeting of any joint committee, joint board or other body by whom for the time being any of the functions of the authority are being discharged, or who were appointed to advise the authority on any matter relating to the discharge of their functions, and attendance as representative of the authority at a meeting of any body of persons, shall be deemed for the purposes of subsection (1) above to be attendance at a meeting of the authority.