Design fault?
If so then how would the vehicle pass homologation/safety crash test requirements and be cleared to be used on public roads? Having seen Morgan 3 wheelers racing at high speeds on corners then how would a 22mph overturn occur without extra influence?
On a roundabout near us I have seen a couple of cars overturned over the past 5 years. Standard cars. In both incidents the cars were up on their side on the pavement. It would be a case of warp factor 8 to cause without an exterior influence. In my opinion they had hit the kerb and the CG being above that point of contact caused the overturn.
TG have had many high risk stunts with deliberate actions causing crashes. It would be enlightening to see the circumstances and reasons for the payout.