I found a site specifically for GB Airways:
www.gbairways.com (pretty obvious, but I'd earlier staggered into their section on BA's site and thought that was all there was).
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Generous legroom of 31” – that’s up to four inches more room to stretch out than on many charter airlines</font>
Doesn't sound very "generous" to me. But then they boast of a 34" pitch in Business Class.
andrew