anglepoise desk lamp with obsolete lightbulb fitting (islington N1)

I am offering this genuine Anglepoise desk lamp in full working order.

However, unfortunately it has an obsolete lightbulb fitting (see second photo) and I can't find a bulb for it anywhere. It will therefore only be of interest to someone who is able to change the lightbulb fitting or who knows about stockists of obsolete lightbulbs I am unaware of!