Whilst researching Richards Battery RGA it transpired  they were equipped with French Guns. Thanks to the help of GWF Pals I found out  two Siege Batteries, the 105th and 106th were also initially equipped with French guns. It became apparent all three batteries experience of manning French Guns was intertwined.  

The 105th and 106thSiege Batteries deployed to the Western Front with personnel only. They arrived in theatre on 17th May 1916 and proceeded to Le Parcq, 30 miles east of Arras.

105 Siege Battery were issued with 4 x 120 mm long guns, and after a period of training were assigned to XVII Corps Heavy Artillery located in the Arras Sector. 

The battery fired its first rounds on the 10th June 1916.

French 120mm Long Guns

106 Siege Battery took over 4 x 220 mm mortars on 27th May. The war dairy records the guns had no wheels, no limbers, no ammunition and were deficient in stores. The guns and what stores they had were loaded onto lorries and the battery moved to billets in Tinques, 15 miles east of Arras. The Battery officers and 8 NCO's proceeded to Arras to receive instructions on the use of the French Mortars from a French Battery in action.

220 mm TR mle 1915/1916

After a period of training, the personnel of the battery proceeded to La Targette 6.5 km north of Arras, taking over guns and stores in position from a French Battery, on the 9th June 1916. They would register the guns before being ordered on the 14th June to proceed to Abeele, near Ypres. They took one of the four mortars out of action , leaving three in situ. (WD 106 SB - June 14th 1916).

It would now seem that there were three mortars that were required to be manned. On the 16th June, Captain DJR Richards from 105 Siege Battery formed a new battery. It would later take over 3 X French 220mm' guns', at La Targette, presumably those left by 106 Siege Battery. With no establishment, it would seem Captain Richards would need to find some men to man the 220 mm Mortars. He received details from 105 Siege Battery, who would have knowledge of working on French equipment, and 51st Trench Mortar Battery, who would understand mortars.

As this was ad hoc battery with no establishment and no British Guns, one would think it would have fallen outside of the numbering system, hence it's title being taken from the Battery Commander, a practice used by the Royal Artillery before numbering systems came in.

The ad hoc grouping would take over 3 x French 220 mm Howitzers on 21st June, and were supplemented by  80 other ranks of the 51st (H) DAC. They were assisted by  French brigadier and two French JNCO's, firing their first round on 26th June.

Captain Richards, to whom the Battery was named after was posted to back 105 Siege Battery to take command , and the men from the 105th SB returned to their unit.

The two French equipped batteries (Richards and 105 SB) remained in action  to September 1916. Richards Battery remained at LaTargette, firing for the King on 9th August 1916. The last record of the battery was a shoot on September 3rd. 105 Siege Battery would move to the Somme sector on 3rd July 1916. It handed over its French guns on the 18th September 1916, re-equipping with 6 inch howitzers.