The bottom of the page says "summer schedule" so might just be referring to the usual seasonal change where BA operates 2 flights. But with SAA pulling out of this route, could this possibly be permanent? Ofcourse IF SAA pulled out because of less demand, it casts doubt whether increased frequency by BA on a permanent basis would happen.
In my last 2 experiences over Easter travel, the flights have been completely full(judging from the masses at check in), not sure if the demand remains that high over the dreaded CPT winter. Interesting times ahead.