What a bummer! There I was, looking forward to constantly admiring my new (expensive) Hagon shock, complete with red spring and shiny body, when I realised it's hidden away in the bowels of the bike and will never be seen again. The attached poor-excuse-of a photo shows a final glimpse of it. On the positive side, the bike now goes over bumps with a gentle rising motion rather than the shuddering crash of before.
Thanks must go to young Nick of Revolution Bike Tech in Kingston, who not only fitted it in double-quick time, but bled the front brake, cleaned up the pads and brought the braking up to an almost adequate standard. We'll be back there for more improvements quite soon.