For tax purposes generally speaking a friendly scrip T/O would...

For tax purposes generally speaking a friendly scrip T/O would not represent a CGT event .. it's basically a name change

and that is all that matters .. the only time you need to consider tax is the point at which you receive proceeds from a sale or income from a dividend or annuity etc etc

your holdings simply change from MEP to ADN ..

of course eligibility for a CGT discount in the event of a sale is generally established by the date at which the original equity was purchased, not the date at which your shares change name