1900 - 1920 Henderson bagpipes
John Grant of Edinburgh owned these pipes and wrote and published privately a book entitled Piobaireachd, Its Origin and Construction (1905). It communicates his enthusiasm and is worthwhile reading, if you can find a copy. He is said to have been an indifferent player. In 1919 he was appointed Instructor at the Army School of Piping in Edinburgh Castle, but (according to Bridget Mackenzie) was dismissed as incompetent after only a few months.

Pictured here is a set of great highland bagpipes, the drones and chanter of blackwood, with engraved sterling silver mounts.  The chanter is stamped “P.HENDERSON / GLASGOW” and engraved on the chanter sole “JOHN GRANT / 28TH NOV / 1902 / 29TH NOV / 1896”.  Also engraved on a silver plate on the bass drone stock “IAIN GRANND / 28TH NOV / 1902 / 29TH NOV / 1896”.  The silver plaque and the chanter sole hallmarked for Glasgow 1903. The leather bag with Grant tartan cover. The blowpipe not original, but made and decorated with sterling silver in similar style. With practice chanter and bag,  silver mounted, signed "P.HENDERSON / GLASGOW" Hard leather carrying case, worn. With three volumes of piobaireachd music, one printed, the other two in manuscript. The former owner was a famous player and composer.
The Henderson above is said to be from 1910 and lines up favorably with other early examples.  Pictures like this help us see the profile and certain details.  The picture at the left is critical to get an overall sense of the profile of the bagpipe.
The best of both worlds.  The silver is hallmarked 1908 with ivory projecting mounts.  Using this we're able to draw comparisons in the style and turning with other bagpipes and establish a probable year of manufacture.
This is outstanding!  The bagpipe with documenation from WWI.  I've included one fabulous picture below. The others were too poor in quality to publish.
Here's a case where the material used helps us to establish age.  The imitation ivory is casien and Henderson used this prior to catalin, which became favored after 1920's.
George Day was born in 1878 and was a student of Inverness Gold Medal winner John MacDougall Gillies.  He apprenticed in Henderson's shop prior to immigrating to Canada in 1906.  He made the set of pipes pictured herein.  Cocuswood with aluminum fittings, which was considered a precious metal at that time.  The tuning sleeves appear to be the work of Duncan MacRae.  More can be found on George Day in Barry Shears' book "dance to the piper".
The set immediately above is unique.  It was a presentation set where the plaque is hallmarked 1915 and refers to a presentation date of 1916.  The silver fittings are hallmarked 1914 and are cast.  Actually they were cast in pieces and soldered together and then had additional detail "chased" throughout.  Oh yeah, the design?  The same dragon design as found on Calum Piobaire's Henderson bagpipe dated 1865.  I believe that the silver was a retro-fit.  Why?  No hemp stops.  I'm pretty certain that this would not have been overlooked by the original maker.
Makers of Old Bagpipe Place Home
The last (for now) Henderson from this era is a stunning example of their work in ebony.  I didn't get the opportunity to play this bagpipe however I'm pretty sure it would be a show-stopper.
The Bagpipe Place Museum