Join Date: Feb 2009
Location: From ORK, live LCY
Programs: BA Silver, M&M*G, HH Gold, ABP, Seigneur des Horaires des Mucci
Posts: 14,920
If missing a day would really screw you up, book the two-hour connection.
On the other hand, if you book the one-hour connection and a delay on the inbound from ORD causing you to misconnect and be late into PSA, BA owes you €600 compensation, overnight hotel in LHR, and all your meals.
I've done a connection at LHR T5 which was reduced to 50 minutes by late arrival of the inbound aircraft, and it went fine. I have fast track security due to my BA Silver status, though, so it might have made a difference.