BabyBlueOnline (interesting comment blog on anglican stuff, drop by) has this, on an essay by Bishop Tom Wright:
'All Souls Langham Place is stuffed to the rafters with his fellow Englishmen and Englishwomen who are gravely concerned that indeed that is an iceberg ahoy and one either needs to navigate around it or hit it. But my dear bishop, sticking your head in the sand and saying 'not here in England,' brings up images of that unfortunate prime minister, you know the one - he came just before Winston Churchill.'
So, to try and explain...
We are in a church. An iceberg is seen and the bishop (presumably therefore the church is on a boat of some sort) reacts by sticking his head in the sand. A fire bucket-full perhaps? Or just a long neck that reaches the shore? And this brings up images for the writer of an appeasing Prime Minister with a piece of paper guaranteeing peace. Not for me it doesn't. I have an image of a church stuck in an iceberg and a bishop trying to get a bucket off his head.