Yes, and you can still buy it.
But, i presume, not readily?
There is quite a lot of standed 2.5mm twin and earth around here in schools and similar, installed in the 1990s, it was favored by the electrical division of a large buidling firm, they are no longer in business and ive not seen it on jobs done post about year 2000
On the flip side, why did solid 2.5 6491x singles ever exist? dosn't pull through very easily!