Toby wrote:Is there a story to go with this?
Haha.. well yes and no. I've been working on-and-off on a project of building my own forced-air system. I just needs a few more bits and pieces and i'll be able to test it out. Coupling to the BBQ was one of the hurdles - but googling around I borrowed various ideas and came up with this system which seems to work - and without damaging or drilling into the BBQ itself. On the other side of the screw head you see, there is a spring toggle clip similar to this attached through one of the vent holes:

On the outside you see a brass compression fitting for a 28mm copper pipe (standard size used by plumbers).
This is all mounted on an 11cm pet food bowl - available from most good pet shops.
As it happens, standard dishwasher drainage pipes are 28mm at the one end- how convenient - and cheap - 3 quid from ebay.
In any case, even if you are using someone elses forced air system - this could help anyone wanting to couple to their BBQ.
A few things I might need to do - stuff some aluminium foil or use aluminium tape over two of the 3 holes holes in the vent i'm coupling to. Apparently forced air can overwhelm the pit with air unless you do this. I may also add some flat stove rope to further make the connection air-tight, but it is pretty flat as it is - i'm not sure if that will be necessary.