[rlmw]

I can somewhat see your point, but the house of lords is primarily aimed at redrafting/refining legislation, and can be overruled under the Parliament Acts[0]. So it is possible to pass legislation without the permission of the House of Lords, but it isn't possible to pass legislation without it passing through the Senate afaik. Obviously legislation thats passed the senate can still be vetoed or stopped by the House, but thats a different thing.

[0] http://en.wikipedia.org/wiki/Parliament_Acts_1911_and_1949