Ok I think I'm being too precious about these tests passing, I now see that the reason the Socket.t test fails is that my router doesn't listen on port 7 - hence 'connection refused' in the strace.

Looking through strace on the actual failing application, I can see the issue is missing modules. LWP not finding Net::HTTP being one of them. I will rebuild my perl installation and monitor strace for missing modules.

I presumed I'd get some sort of warning on the command line, sorry I'm still an amateur with perl..