The message
from Ian Stirling contains these words:

SDS is not needed -

You've not tried the walls round here.

Using even very good quality masonry bits, in a hammer drill or hitting
the end with a hammer, just didn't go in. I've drilled holes in masonry
all over the country in various jobs, but for well aged concrete SDS is
sometimes the only way to go.

Other people in the row have had the same problem - nothing will go in
in a reasonable [1] time.

[1] Less than half an hour of sweating and swearing.

--
Skipweasel
Pay no attention to that man behind the curtain.