A number of Government Bills begin in the House of
Lords each year, and are passed on to the Commons for
consent. They start in the Lords for various reasons -
perhaps because the Bill is of a technical rather than
political nature, the Government Minister introducing it
is a Lord and also to balance the load of legislation
between both Houses.
The most important and controversial Bills usually begin in
the Commons - and all Bills to set taxes must begin there.
However, there is also a convention that Consolidation Bills - which do not alter the law but wrap several acts up into a single piece of legislation - should start in the Lords. These usually take up very little time on the floor of the house as they are considered chiefly by a joint committee of Lords and Commons.