Twenty days in each session are set aside for debates on subjects the Opposition choose. The Leader of the Opposition gets 17 days. The other three days are allocated to the third largest party in the House.
If a session lasts longer than a year, the whips may agree on a further number of Opposition days. And the Government may provide further ‘unallotted’ Opposition days, even in a normal year-long session. Some of these might be used for the smaller parties.