Patented in 1910 with the number 19234, the Rexos Automatic Spanner was distributed - and possibly manufactured - by Alfred Herbert Ltd. of Coventry.  Described as having a self-acting release, it was unnecessary to left the spanner off a nut or bolt head, the spanner working as if equipped with a spring-loaded ratchet  - through without the ratchet or the spring. The Rexos was made to fit Whitworth nuts in sizes of 1/4", 5/16", 3//8", 7/16", 1/2", 9/16", 5/8", 3/4", 7/8" and 1" and could be provided in set in "strong roll-up bags". 
Made from a forged and case-hardened steel, the loose jaw pivoted on a pin, the design ensuring that the pin acted merely as a hinge with no load upon it as the spanner worked. But, did it work and was it a success? Today, a trickle of examples turn up on auction sites in former British colonies, so it must have been widely exported - the later No.2 version from 1912 shown in the last picture below is in Australia. However, the advent of sockets and ratchet bars would have made it obsolete - through today a modern replacement is available in the form of spanners with a built-in ratchet ring at one or both ends - a design first seen by the writer on the French market during the 1970s.
The Rexos publicity literature reproduced below was found in a folder with printed literature, pencilled-in dates and letters from 1913. The advertising "puff"  - "The greatest time saver of the century" and "The greatest labour saver ever invented" - might be considered just a little wide of the mark. The cost was also considerable, a full set being priced at £2 : 14s: 4d at a time when average manufacturing wages varied between £1 : 6s : 4d and £1 : 14s : 0d per week. Today, in 2020, the cost of the spanners, based on the "Historic Standard of Living Index" would be around £265.

A Rexos No.2 spanner with a patent date showing 1912. This example was found in Australia