I think the Austin company instructions went from 1/8" toe in on the early cars to '0' toe in sometime in the mid 30's back to 1/8" toe in at the conclusion.
I don't believe the slip angle with age hardened radial tyres on an Austin 7 would be a consideration- more of interest is the slightly flexible track rod and worn connections making a toe in at least 1/8" probably the best alternative.
The camber, castor, any king pin inclination, all influence the pull tending to open the wheels. The degree of spring in system a factor.
All a bit academic with Sevens because of the coarse adjustment (unless, as often, the track rod is deliberately bent) I dunno how owners consistently get high tyre mileage from Sevens without some brutal bending.
There can be few cars more simple to check and measure than Sevens. For moderns really need an awkward external calliper contraption as so low.
On cars with significant tow out, an annoying conscious effort is needed to initiate slight turns.