Sputnik Replacement Bulb

[WeeboTech]

Asking for a friend, does anyone have information on a replacement bulb for Mathmos Sputnik?
It's been so many years since I had one I can barely remember much about it.
Any Information, links or offers for a spare would be appreciated. 

[Johnny]

reckon it be a standard 40watt golfball  Small Edison Screw Cap (SES / E14) as used in the astro's and jets when these came out

[WeeboTech]

Thank you