All I can say is that I SINCERELY hope that these are merely trolls by some feeble-minded individuals. If not, then "rather keep quiet and let people think you're an idiot, than open your mouth and remove all doubt." Apart from some other factors mentioned, bear in mind that Chalkie operated in controlled airspace at times, where radios are mandatory. Hence a few hours delay for radio repairs, which Alex would not have had. Then of course there is the legendary African beaurocracy these days, which was probably non-existent in 1939. Hence a few hours delay for paperwork and refuelling, which Alex would not have had. Shorter stopover halfway? Sure, Alex had that option too. Navigation? Without a doubt Sir Henshaw will have encountered far more difficulty here. Will Chalkie have been able to do it with no GPS etc? I have no doubt he would have, but with reduced safety levels. Different times, different challenges. Now if it's so easy, why don't the big talkers build a plane and go beat it? I dare you.