Thanks for those suggestions corporate_gadfly !
but have you tried cURL with the -F flag?
No I hadn't - but I have now (as well as a few other data flags). Sadly, no difference.
wget only supports application/x-www-form-urlencoded
Indeed so and, according to Tamper Data, that is the way Firefox sends the data so I thought it should be OK.
The really annoying thing is wget works fine so long as there are no characters that need to be urlencoded in the data so
wget 'http://admin:admin@obihai/result.html?fecc8d44=ph'
works fine but
wget 'http://admin:admin@obihai/result.html?fecc8d44={ph}'
or (clutching at straws)
wget 'http://admin:admin@obihai/result.html?fecc8d44=%7Bph%7D'
don't.
I'm sure I'm missing something obvious!