Mostly good stuff – but no need to leave one at home – the whole point is to travel with both??
Just remember :-
-NEVER change passports in a foreign country – always do it in the international space or UK
-it’s a uniquely british privelege and some goons will not be understanding – be patient while they satisfy themselves and avoid if possible letting them see more than one
– it is VITAL in the letter to passport officer to specify which countries you will visit (the examples above are perfect)
– FCO Consular staff can be more understanding and helpful than UKPA staff