DISRAELI DOCUMENTS
This patent describes the Ihaga S.A.G. derailleur in this collection. It lists the inventor as Jules Hendrick of Liège, Belgium. We could guess that Ihaga was Mr Hendrick's brand - as JH (his initials) and IH (the first two letters of Ihaga) are sometimes interchangeable in Northern Europe - but this is all a spurious guess.
The derailleur itself is a rather elegant top-normal design.