Now looked in my book, Ken Hill's "Completely Morgan, Three Wheelers from 1910 to 1952".
LTOW is also shown there as 40 bhp, but LTOWC as 42 bhp. The final C stands for sport specification I'm told, but I think the engine is really just a higher compression version with the (de)compression plates removed. It's logical that an extra 2 bhp at the same revs is compression or breathing and not a cam change.
1930 Super Sport Aero 'The Elk'