I think the Monarch and BA '757s' are of the A320 family.
Not easy to be sure from that angle but the bogie undercarriages visible below the BY machine's tail must belong to either the BA or MON machines.
AFAIK such a set up was available as an option on the A321 but only taken up by an Indian company operating onto low LCN runwys.
So at least one is a 757.