Just a couple of answers for the time being :

The rifle is a 'mismatch' (as I think you knew) - the important two numbers that should match are a) the action and b) the bolt.

The "Englandicon" is the pre-1968 USAicon import mark to show country of origin.

The "2.222" 303 18 tons per sq inch" are UK civilian proof marks required when it was sold out f service into the UK civilian gun market.

The forend looks to be a little worse for wear.