(1) For the purposes of this Part, a person (''A'') increases control over a UK authorised person (''B'') whenever -
(a) the percentage of shares which A holds in B or in a parent undertaking of B (''P'') increases by any of the steps mentioned in subsection (2);
(b) the percentage of voting power A holds in B or P increases by any of the steps mentioned in subsection (2); or
(c) A becomes a parent undertaking of B.
(2) The steps are -
(a) from less than 20% to 20% or more;
(b) from less than 30% to 30% or more;
(c) from less than 50% to 50% or more.