I assume this is the current recipe? My main comment would be that 5.37% is way too strong - you're worrying about a gram of malt to get the colour right but the ABV is simply way out. If you're interested in tradition then >95% of British bitter is under 4.5% and a majority of that is 4% or less. But a best of around 4.2% is probably the first place I'd aim for.
35IBU is on the high side - fine for a northern bitter (my preferred style, you may not be surprised to learn
) but a bit high for a southern one which tends to be a bit more malt led.
Whilst a Fuggles/Goldings mix is a classic one, I'm a big fan of Bramling Cross, it's a nice one to have as a late kettle addition but obviously if you're only doing one gallon then you don't want to go too mad on buying hops. We talked a bit about hops over in
another thread - I'd also emphasise the point about 2016 being a poor vintage for hops, and at this time of year any hops that haven't been stored in perfect conditions will be feeling pretty tired. So you might want to up your numbers if you're not sure about your hops - or wait for the new season hops which should be coming soon (they're mostly harvested by now, it's just a question of them getting into the supply chain).
A lot of the adjuncts you see in recipes aren't particularly "classic" - they just reflect industrial breweries trying to make cheap beer. Like rice in US lagers, they kind of take on a life of their own as being part of a style, but they're not essential. And I wouldn't sweat the colour too much -Boddingtons bitter is almost the colour of lager, historically it was always an outlier but golden ales are now pretty much an essential part of a British bar. I'm not saying you should brew a golden ale, but Maris Otter or Golden Promise, plus some crystal, will make a perfectly respectable British bitter. I'd be tempted to add a little torrified wheat (like 5%) if you can, but again I wouldn't sweat it - there's a whole quasi-religious debate about the nature of head on British beers, but let's not go there!
As for Bass - one of the most bizarre decisions in an incredible story of brand destruction was to advertise it as the first trademark in Britain. But then that's what you get from ABInbev. It wasn't the first pale ale, by about 200 years, but the red triangle was the first trademark registered. Since the brewery got sold off (eventually ending up with Molson Coors) it's been brewed in various places - cask for the UK is contracted out to Marstons, AB brew the bottled version in the old Whitbread lager factory north of Manchester, but I think they still brew for the US market in New York state (and it's also brewed in Belgium for their local market). The general conclusion is that cask Bass isn't quite what it used to be but can be superb if fresh and kept by someone who knows their trade, it very quickly turns dull though - finding good Bass is something of a quest among a certain type of CAMRA member - but the bottles tend to capture all of the dullness and none of the greatness. I can't imagine what it must be like brewed in the US. ABI have pretty much killed it as a brand and as a beer in the UK, you really seldom see it except in supermarkets. But at least it gives you some idea of what you're aiming for.
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