This would probably qualify for This Is Broken, the archive of flawed user interface design. It's the Royal Mail's Postcode Finder utility; type in the address and hit 'Search' for the postcode, or switch to the Address Finder, type in the postcode and search the database for one of 27 million addresses. Simple, and useful (if one hadn't been required to log in to even access it – I used a fake Bugmenot ID, of course).

The button design is... mixed. The distinction between the grey 'Help' & 'Clear' buttons and the red 'Search' button is good, but user familiarity with conventional form layouts means it's all too easy to click on the big, more obvious, red button without reading it, and flip to the Address Finder, clearing the text already entered.

Picky? Perhaps, but if the browser's autocomplete dropdown appears when one types into the 'Town' box, the 'Help', 'Clear' & 'Search' buttons are completely hidden, and one naturally clicks on the only available button, wiping the entire enquiry.

Still picky? Okay, yes – I doubt 'This Is Broken' would be interested, really – but this could have been avoided so easily, with even the slightest pre-publication user testing. I'm not complaining about the magnitude of the error, but the apparent lack of thought.