I see in the '35 ST catalogue that they show the
AE twin as 0.5hp @2k rpm, 0.75@3k, & 1.3@4.2k.
There's no mention as to how old, but there are no
testimonials re performance, which ST often liked.

The AE single was definitely winning model boat
races in 1932.

Same catalogue shows a very pretty 30cc Lightweight
engine, sitting in someone's palm. £9 complete.

The Sandhurst is described as designed for engineering
students at the Royal Military College, Sandhurst. Funnily
enough, it is given as 2x3", 'tho as Peter says ST use metric
dimensions elsewhere in the catalogue -- the British have
never quite got the metric thing .... No date of introduction,
'tho the text reads as if it were a recent addition -- but,
knowing ST, I wouldn't put it past them to use the same text
for the lifetime of the engine. £8.75p for the whole caboodle,
you do the machining. 40p if u want them to machine &
grind the cylinder bore.

The 600 was largest & best of all. 0.75hp@700rpm. 2.5x4.5"
£6.87p approx, bare. There are a few on the rally scene.

Colin