OK, so airport lounge has free wifi, as it should.
Only trick is that they seem to be lacking a DHCP server at the moment!
A quick tcpdump shows a lot of NETBIOS packets from 169.254.x.x and lots of unanswered bootp requests. Ho hum. A lot of puzzled faces curing at their laptops too.
Thankfully it was pretty obvious what network was in use (192.168.0/224) and gateway (192.168.0.1), and the hotel's DNS servers still in my config worked as well. So I have wifi!
How hard can it be to get things like this right FFS.