In reply to Graeme Hammond:
> It could have fallen out anywhere on the decent and been quickly covered by snow so not easily found at the time for months, it could even still be a far corner of the gully...
All this time later, it is highly unlikely that it was just lost. Several of us looked down the central groove which we had come down, both that same night with head torches, and the following morning. Observatory gully at that time was full of people. We advertised in these threads. We rang both guides and climbing shops etc. We were staying at the CIC, the obvious place to deposit a found piece of gear. It was not lost at the periphery of the gully. I have been up when there has been no snow. The ice-axe was colour marked.
I suppose that you would also suggest that the ice-axe which I had hidden under my rope in the lower floor of our first hut in the Swiss Alps of a certain trip, several years previously, overnight, had just got lost, when I found it missing in the morning. That particular Black Diamond axe had never been used. It was the reason that my girlfriend got me the carbon fibre axe as a present.
By the way, I being sorry for the OP, having been in absence of my axe, on two occasions at least, did reply to him in good part to get his post noticed. So please go and get his axe delivered to the rightful owner if you know where it is.