Pictures of a very special Gibbs 303 sent to me by another member of NitroExpress.
I have to admit, this one really makes my heart flutter!

The following is the owner's message to me with some information on the gun:

Huvius,
You are very fortunate to have aquired such a lovely rifle,I also have a Gibbs Farquharson which is almost identical to it,but without the wrist positioned sight,which I think was fitted to some later rifles than mine,my use number is 845,with a serial number 17330,which I think puts it at around 1890,the Gibbs records having been destroyed by "enemy action" I have no way of knowing exactly what the DoM was. As you observe,the case lable is unusual,mine has the Corn Street address,but is completely different to yours,my rear sight base also "overhangs" the barrel by a lot,implying that it was originally of larger caliber,the sight also has engraved upon it "Powder 37 Grs Cannonite & Bullet 200Grs" , I have searched charts and books to find just what caliber used this charge ,but so far without success,it is in .303 British now,which has the same cartridge head size as the .375 X 2 1/2", but I do not think that cartridge dates back that far,mine is also fitted with "Selous Plates" which seem to be quite useable even in 45Degs C heat!

Just LOOK at those plates and the timed screws!