Yes, thanks for the reply.
We wondered whether the 30 mins was the time given to descend from overhead the beacon associated with your destination.
What we weren't clear about was whether you were supposed to descend to make good your ETA or EAT (if given) or arrive overhead at cruise altitude, then descend to arrive at up to ETA plus 30 mins.
It's still not absolutely clear but your reading is much the same as ONE of our options.
There MUST be a defintive answer out there but looking in the Jepps the 'black and white' isn't fully clear to me - who is English and so is the text but someone moved the interface out of sync!!!
Am I just thick?? Or was it written by lawyers?