Indeed my poor daughter who is holding her 50th birthday party in Germany next month has had to come to terms with the fact that I shall not be joining her on the day.
It won't get you to Oz, but I'm in Avignon at the moment - having got here in a very relaxed 6 hours sat on a train (and a very nice 3-course French lunch en-route).
This reckons you'll get to Cologne in about 4 hours from London with one change in Brussels.
Just thought I'd mention it. I know we are all aviators, but just occasionally the train is a very pleasant and affordable way of getting around Europe (There are even still sleepers out there - London-Edinburgh, or Paris-Berlin for example.)
Maybe you can surprise your daughter yet!
(Better still, hold out for our Australian cousins paying up for a cruise ship! - don't disembark, you can lecture on board so should be safe from your Mother in Law's agents.)
G