Another option to consider is the improved Virgin Atlantic Premium Economy. Virgin flies to both Capetown and JNB from London. It's basically the same as a US domestic 1st class seat. Here's their website touting the new product:
🚢 Cruise with your favorite Keene Luxury Travel Staff Member! 💰 5% KLT Reward plus Shipboard Credit available (amount varies per voyage)! 💲 Offering Enhanced KLT Rewards on voyages hosted by Ngaire & Clay!