"Usual channels" is a term used in British politics to describe the relationship between the whips and leadership of the Government and the Opposition.
Essentially, this is to obtain co-operation between the two parties, in order to ensure as much business as possible can be dealt with in each parliamentary session.
[1] Negotiations in the "usual channels" take place daily, with the key roles being played by civil servants such as the Principal Private Secretary to the Chief Whip.
They determine how the time in each house of Parliament is spent and, prior to the 2010 general election, they decided the composition and the chair of select committees.
In 2002, the Hansard Society published a report entitled Opening Up The Usual Channels, which concluded that the Commons would benefit from greater transparency if the system were to be replaced by a formal "business committee" as used in other legislatures.