Labor caught out the Coalition government at the end of a fractious first week in the 45th parliament, using smart tactics and parliamentary procedure to severely embarrass Malcolm Turnbull and explode the prime minister's claim to have a strong working majority.

Here's how it went down.

The opposition's push for a motion calling for a royal commission into the major banks was defeated in the House on Wednesday.

It then moved on to the Senate and, after discussions with the crossbench, it was quietly passed on the voices around lunchtime Thursday - with a rider that asked the House to debate the motion again.