Oh oh Preston ('Q'), you're making my 'Editor's Eye' work overtime.
It's a good thing these stories are fantasy, because at the rate Uncle Charles & Lord Tyler are spending like drunken sailors, Hunter Investments Pty and the Earldom purse may soon be empty.
Reality cheque (pun intended) Tyler's £200 Million inheritance (at start) is largely property and NOT COH (Cash On Hand). Abbey & Estate (open to tourists), Castle & Estate (closed) Amanda's Home, + 11 acre Seaview bolt hole + desalination plant in OZ are not cheap. Detached homes on Amanda's street range £1.5 - £3.2 Million. Abbey, Castle + estate lands easily £50 M. Mary & George's 1/4 acre waterfront detached on Seaview cheap at around £300K, 11 acre Seaview home maybe £10M. 3 existing Desalination plants in OZ average $15-20 M Aus each. A 'small' plant for station / farms maybe $2.5M even after selling off the resulting salts.
BTW the new Hunter Inv PTY purchases of farms, estates & commercial properties on IoM & IoW (Isles of Man & Wight) = 914 acres not 750. Ave cost = £25 - £40M total. Even as working farms/estates that you say "cover the taxes", and with only the Abbey doing tourist tours (soon 3 days a wk from 1) breaking even? For reference Buckingham Palace - largest castle visited - is only open to tourists 10 weeks a year (Aug, Sept and 1 week each during school breaks in Dec and Easter) generates approx £35M yr net.
Just the facts.
Hopefully Lord Tyler's keen mind and skills (from the station in OZ) will help him balance the books before Charles departs (leaving CA$H and no debts).
'Please Sir, can I have more' ;-)