I'll have a stab and if I get it wrong someone on here will correct me.
The chassis plates shown are normally associated with older Series II splitscreen cars whereas your Chassis number starting with 701 denotes a car from 1959.
A new style of chassis plate was introduced in 1958 which is oblong with rounded ends so that has confused me for a start.
M/A2S3L is decoded as A Series Engine 2dr Saloon. I'm not sure what the 3 denotes (it could be that it was originally painted in cellulose) and the 'L' denotes Left Hand Drive. There is no 'D' at the end of the sequence so the car is a standard saloon.
The chassis number dates from around April 1959.
So the car should be a LHD (Series 3 Export Model) 2 Door Standard Saloon with a 948cc engine painted in a mid grey cellulose paint.
If you go to the Series MM website http://seriesmm.mmoc.org.uk and click on car identification then go to chassis no. identification you will find a complete explanation