The feedback was that if one of our number had an accident which caused considerable fatalities over and above the insured sum (as death and personal injury cannot be limited or excluded by law) then the other registered owners of the syndicate (including the possibly now deceased pilots estate) would be liable.
This is correct. The Civil Aviation Act 1982 establishes a strict liability of owners of an aircraft for damage that the aircraft does to persons and property on the ground.
76 (2) Subject to subsection (3) below, where material loss or damage is caused to any person or property on land or water by, or by a person in, or an article, animal or person falling from, an aircraft while in flight, taking off or landing, then unless the loss or damage was caused or contributed to by the negligence of the person by whom it was suffered, damages in respect of the loss or damage shall be recoverable without proof of negligence or intention or other cause of action, as if the loss or damage had been caused by the wilful act, neglect, or default of the owner of the aircraft.
Having a limited liability company own the aircraft avoids personal liability, except of course where personal negligence contributes in some way to the damage.