The Highest Possible has been a very elusive item, perhaps because so few were ever made which then had to survive the next 100 years. I have no exact records of the production figures but the Collectors Guide to Air Pistols by Dennis Hiller suggests that the highest serial number known is 1052 suggesting only 1000 odd were ever made.

Engraved on the L.H.S of the air chamber "WESTLEY RICHARDS HIGHEST POSSIBLE - AIR PISTOL". On the frame near the sear is stamped the serial number, 369, which also appears on various other parts. On the left side of the frame is engraved "WESTLEY RICHARDS & CO. - LONDON W" and near the action latch appears "PATENT 24837 1907". The pistol has black chequered vulcanite grips and a 9 3/4 inch rifled barrel. Rear sight appears to be adjustable for elevation only. Length from tip of barrel to base of butt is 12 1/4 inches. The above design was patented by E. Anson, a relative of W. Anson of the well known partnership Anson & Deeley. The "Highest Possible" was also available nickel plated. Highest serial number seen is 1052. Inside of grips are usually scratched with the serial number of part of it and the rifling appears to be anticlockwise. ( From Air Pistols by Dennis Hiller)
The above sequence of photographs shows the cocking of the air pistol.

Ted Harris on January 9, 2015 at 2:48 pm
Dear Simon,
Thank you for the very interesting article regarding your acquisition of a Highest Possible and the superb photographs. I came into possession of one many years ago, in quite crisp condition, missing only the hand grips, (which had been replaced by home-made wooden ones) and the rear sight. unfortunately, the trigger had been broken at some time – not sure how this could have happened as the construction is somewhat bomb-proof, but has had a repair using a bright metal, which looks fine. I don’t suppose it would be possible to still obtain hand-grips? I will make use of your photographs by scaling up to life-size and attempting to recreate the grips – and the rear site. If you are interested I will forward some photographs with serial numbers etc. Again, many thanks for the article – and all the others in the The Explora and compliments to your excellent photographic team.
Andrew Robinson on January 10, 2015 at 4:46 am
Hi I have owned an origional bright nickle pistol with horn grips for some time now, it is the only nickle one I have come across, it retains 80% of the origional finish.
Any info would be appreciated.
Andrew Robinson
Mike Post on December 24, 2014 at 6:03 pm
hello every one ….
I have a very good condition. Westley Richards air pistol and looking to sell it ..
Can any one guide me to the right place to list it for sale ….
Simon Clode on December 24, 2014 at 7:01 pm
Send me a picture and a price theexplora@westleyrichards.co.uk I would be interested.
Simon
Rick Pascoe on July 20, 2014 at 4:16 pm
Dear Simon,
I have what I presume to be a Westley Richards Highest Possible air pistol although it is not marked as such. The serial number is 712. The pistol is stamped “The Unity Air Pistol” on the left hand side of the spring housing. The left hand side of the frame is stamped “Shimwell Bros. South Africa” and “Patent 24837 1907”. I actually worked for Shimwell Bros i the 60’s and know that the company was formed in the late 1890’s and closed in the 1970’s. They were dealers in arms and ammunition as well as Triumph and BSA motorcycles amongst other things. On the arms side “Unity” was the name used on firearms and ammunition that the imported from various suppliers. I think that this was because the Union of South Africa was formed in 1910. Your comments would be appreciated.