My first flights as a kid were from 1964-1968 always on British Eagle or BEA from LAP to BCN VCE RMI AGP VLC and PMI
We always checked in usually at the London Air Terminals and took their coaches out to LAP, but a couple of times we checked in at the Europa Building (T2)
I recall European and Domestic flights operating from there and the Oceanic Terminal opened in 1962 handled BOAC etc...
Re the 1955 video above shows the new QB, the tower and the Europa Terminal, So my Q is before the Oceanic Terminal was completed were all the transcontinental and long hauls still handled over at North-side?