If he departed UK on 24 June, iirc, the latest date of departure from last stopover point must be within 1 year
What I cannot remember for certain is whether latest departure from last stopover point would have to be the 23rd of June or the 24th of June
either way, I cannot see him being permitted to stopover for 3 days in Dubai since , whether the last date is 23rd or 24th, the 1 year validity would limit this stopover