In message , BH Williams
writes

My recollection of visits to Waterloo in the late 1960s suggest that at
least part of the site of Waterloo International was carriage sidings, along
with the lift used for stock exchanges to the Waterloo and City.

Correct. There were also a couple of large old BR office blocks, roughly
where the new taxi drop-off road to Eurostar is now located.

Incidentally, according to wikipedia, the Eurostar terminal was started
in 1990 and opened in 1994.

--
Paul Terry