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