Amberss. There are two 'schools' in target
Longbow in GB. One which is fascinated in the history and traditions of the
Longbow (understandable) and another which regard it in modern terms of being just as deserving as the
recurve, barebow and
compound classes of respect as a 21st century sporting discipline. The latter will be looking to hit as high a score as possible within the sporting rules, the former will prefer to try to hit as high a score as possible within traditional (usually limiting) 'trappings'. Hope that is fair - no disrespect!
Those in the latter are looking towards Portsmouth scores of 500+ (gents) and 480+ for ladies (don't kill me on that one folks I know ladies shooting over 500) but probably only the top 10%(?) will reach this level. Average scores is a difficult one but look to the DNAA Blaze Classifications (
http://dnaa.co.uk/wp-content/uploads/2016/10/Blaze-Rules-Full.pdf) where the various scores are as near to GMB. MB, Bowman, 1st, 2nd and 3rd as could be estimated. Hope this helps.