It's a damn hard business model to make work.
I tried it a few years ago.
A very narrow market; nearly totally VFR-only pilots (nearly all current IR holders already got their own plane) but ones with lots of money to afford the very high marginal hourly cost.
How did they owe C&E £100k? That would suggest they made of the order of £500k plus in profits during the relevant period. That debt (if true) could not have been from a straight trading activity.