The first Review of the Horseshoe form Pickup by Radio Instruments & Varley, a London based Company was by Percy Wilson in November of 1928. Wilson visited a tiny Island off the coast of Southern England called Jethou with G.W. Webb, his Colleague & future Co-Author of the excellent Book "Modern Gramophones & Electric Reproducers" written in 1929. In Jethou He had the ability to test a number of Early Add-on Electric pickups with a Petrol Generator powered Electric Amplification system according to the article in the Gramophone Magazine.  Wilson's account of the new R.I & Varley pickup was very favourable, He wrote, "When used with loud needles it is the best pickup I have yet heard". The design of the Varley pickup was similar to the J. B. Woodroffe model but for the central needle bar pivot mechanism, instead of a row of rubber rings cut from Sound-box Diaphragm rubber, as found on the Woodroffe, the Varley Company had designed a clever leaf spring, fitted to the needle armature that gave great flexibility without any side play.

The business Address of R.I & Varley was 103 Queensway, Holborn London, W.C 2. This Building still stands & was a mere 5 minute walk from the E.M.G Grape Street Premises & stood as something of a central Hub to the Home Audio manufacturing Community of Central London in the late 1920's, G.E.C had their premises on the same street as Radio Instruments & Varley & had already retailed a similar Horseshoe Magnet form pickup themselves in 1927, under their Brand "GECoPHONE". 

In the summer of 1929, Radio Industries & Varley parted Company & Varley continued to produce their Pickup which was re-badged as "Varley for Radio". 

As far as I have researched, the Varley pickup existed in 4 retailed versions. The type Pictured in the Percy Wilson article looks like a preproduction mock-up & has hexagon form wire terminals as well as 4 fixing screws holding the front Ebonite panel to the Permanent magnet instead of a Casting with fixing lugs built in. Interestingly this pickup form appears in the Varley Advert of December 1928 so may have been retailed in this form for a short period.

There were at least 2 different versions of the more commonly encountered R.I & Varley type, the 2nd of which had a reversible tonearm boss to fit Columbia, Continental & H.M.V tone arms. The earlier type has a single tone arm turned Aluminium fixing with 2 characteristic knurled fins.

The 2 types of "Varley for Radio" Pickups that I have encountered are, an exact copy of the later R.I & Varley type & a later version with a cheapened, frosted silver finish to the magnet & rear mounted wire terminals, it also features an "Automatic needle clutch" that from period reviews was less than sure in use ! & consisted of a "V" slot that was magnetised to keep the steel needle in place on a record. All the Varley pickups were retailed in really attractive Black Leathercloth covered plush boxes with screen printed Logo's in the lid.

From the release of their pickup in 1928 R.I & Varley also offered a Pickup arm that had an ingenious Tracking facility built in. The Varley "Auto arm" also had an Electrical cut off trip device that was cocked by hand & could cut the audio signal when the needle reached the Infinity Grooves of a Record. The arm also had a simple, spring loaded weight reducing feature to vary the pressure of the needle on a record.

The Earliest form of the Varley Auto-arm has a "C" form Pickup tonearm connector fixing, while later examples have a pinch screw to hold the pickup securely in place. The Auto-arm is one of the most flexible pickup arms I have tested as many other pickup types will fit onto it. 

In 1931 Varley produced the final version of their excellent pickup design which incorporated a built in tonearm & used the horseshoe pickup in it's previous form encased & hidden in a bakelite head shell.