I've seen a variation of this ATPL question:-
Upon intercepting the assigned radial, the Controller advises you that you are on the Airway and to "resume own navigation". This means:-
a. radar services are terminated and you are responsible for position reports
b. you are still in radar contact but must make position reports
c. you are to assume responsibility for your own navigation
d. you are to contact the relavant ATC centre at the next reporting point
The answer is given as c., but I don't know whether that's right or wrong - it sounds right.
Sorry I can't help with your specific query.