Exeter had a particularly outstanding musical tradition, and there seems even to be some evidence that the Exeter Cathedral organ may have had an open Double Diapason before the Civil War. What seems to be certain, however, is that John Loosemore’s organ of 1665 contained probably what was at the time the only the Double Diapason in Britain, in two towers detached at the sides. It survived until melted down by Speechly in the nineteenth century. John Loosemore, who built or rebuilt the organ in 1665 after the Civil War, was the son of Samuel Loosemore, a noted organ builder of Bishops Nympton in Devon. John Loosemore was the Clerk of the Works of Exeter Cathedral; that is, in charge of the Cathedral fabric which included being responsible for the organ. He was a genius of his day, but sadly Loosemore’s original specification for the organ of 1665 seems to be lost, and the earliest I could come up with was from the early nineteenth century, by which time the organ had been rebuilt several times.
For what it’s worth, here is the specification given by J. L. Sperling in around 1840:
Great: GG long to D
Open Diapason (West)
Open Diapason (East)
Sex 5 ranks
Mounted Cornet to mid C, 5 ranks
Choir: GG long to D
Swell (added by Bridge): Fiddle G to D
Cornet 4 ranks
Sperling noted that the front pipes of the Choir Organ were adorned with chasing “as at Hereford and Tewkesbury,” which, alas, is no longer the case. It is also unfortunate that the main case has been raised to accommodate more pipes, spoiling its appearance.
Exeter Cathedral organ, seen from the Nave, in around 1790. Though indistinct, this is the only print I have seen where the Double Diapason pipes have pipeshades (?subsequently removed) and where there are embellishments on top of the towers of the main case