An ordinary resolution of the members (or of a class of members) of a company means a resolution that is passed by a simple majority.
A written resolution is passed by a simple majority if it is passed by members representing a simple majority of the total voting rights of eligible members (see Chapter 2).
A resolution passed at a meeting on a show of hands is passed by a simple majority if it is passed by a simple majority of the votes cast by those entitled to vote
A resolution passed on a poll taken at a meeting is passed by a simple majority if it is passed by members representing a simple majority of the total voting rights of members who (being entitled to do so) vote in person, by proxy or in advance (see section 322A) on the resolution.
Anything that may be done by ordinary resolution may also be done by special resolution.