I can assure you that such arrangements are not uncommon when say subsidiaries raise finance and the bank insist on guarantees from both parent and subsidiary as well as charges or debentures on all assets. Whether such arrangements bring down a whole group will depend on a number of factors, such as liquidity of the parent.
I never said they were not (uncommon).
In fact the liquidity of the parent is unlikely to have very much to do with it. The parent company is often little more than a shell, with the real wealth of the Group dispersed around its subsidiaries. For an entire group to fail the failure will turn on position of the group consolidated accounts. For one small company (such as Shoreham) to bring down an entire group, whatever guarantees may or may not be in place, would occur only if there were far more serious problems through out the whole group.
I am lead to believe that at least some of the people involved with Abermarle are also involved with the Erinaceous Group. Albermarle would seem not to be a member of the Erinaceous Group but it might be interesting to know what related party transactions have taken place between the two (if any) and what plans Albermarle now have for the airport.