Low Bb is standard on oboes in the UK, even on the most basic thumbplate system.
The dual system Yamaha 200 series built for the UK market, as well as the basic thumbplate system Buffet (Schreiber) and Bundy (Selmer USA) oboes made specifically for the UK market have the low Bb key and also the forked F vent.
Though most basic thumbplate systems lack semi-automatic 8ves, LH C-C# trill key, the RH C-D trill key (the trill key for LH3 is the C-D trill) and low Bb bell vent.
They usually have the same keywork layout as the Howarth S10, though some may have ring keys and a plain or raised tonehole bush for LH3.
In order from the most basic to the fully loaded Howarth oboes are as follows: