[Thanks for all the info from everyone. Is the CYBI team able to pull off a Fuller's ESB clone? I'd be surprised.
Big Brew 2008 had a recipe for Chiswick Bitter that was pretty close to spot on (I seem to remember that John Keeling had a hand in it). http://wiki.americanhomebrewers.org/BigBrew08
Now knowing that Chiswick, London Pride, ESB and Golden Pride are partigyled from the same mash and having a look at www.fullers.co.uk for gravities - you should not struggle to make your own ESB clone.
Thanks for the info Ant, and all.
In spite of all the info available online from Fullers, not to mention an interview with the Fullers head brewer, the CYBI team bombed it. Wrong crystal, wrong hops, no partigyle. I'm not sure why they bothered, really.