Victorian Organ House

We recently bought a house built in approx 1870.  The house and garden have been neglected for years and while clearing part of the garden discovered a wooden gazebo type building containing an organ.  I have attached photos.  It also is in a sorry state but the pieces of fret work missing from the outside seem to be stored inside.  The family who we purchased the house from, grew up here, they are now in their 60's.  They said it had always been there and thought that it had probably been built not long after the house.

I have spent ages looking on the internet to try and find something similar but to no avail.  Is this a rare thing?  We would like to restore it but are unsure if it is of any value.  If it has no value we can restore it without a problem as we know people who can reinstate the fret work etc. 

Any pointers/advice is welcome.

I wonder if that had been used as a small family church or just for entertaining.  There is a large house near me that has it's own church on the premises and is Victorian-era.  I'm not familiar with an "organ house" per se. 

Love the details and it is just screaming for a restoration.  Would love to see pics of the main home too.

Thanks for replying.  It is not very large maybe 3m by 3m.  It has a bench running around the inside.  We think it was probably used for entertainment due to it's size, position in the garden and building materials.

It is a beautiful piece of history and we just didn't want to ruin it's monetary value by letting a person who is not a proper restorer restore it, if it is worth something.  There are lots of antique dealers around but I cannot find anybody who seems to advertise anything similar to invite around to look at it.