On a topic the conversion of Royal Horse Artillery to Field Artillery was mentioned.

In the book Gunner on the Western Front Aubrey Wade a pre war Territorial in the RHA records:

The brigade, as a whole, was an amalgamation of many small sections of the Territorial Horse Artillery batteries which had been recruited in the early days of the war. Being horse artillery we had always felt rather superior to common or garden field artillery, and were therefore painfully surprised to hear our proud title was to be taken from us , and henceforth we were known as an Army Brigade of Field Artillery".

Being horse artillery we had always felt rather superior to common or garden field artillery,- GRRRRR!*!***!###!!!!! henceforth we were known as an Army Brigade of Field Artillery" - Proper Gunners !!!

Ron Clifton kindly provided information on the Regular RHA

Three brigades RHA (nine batteries in all) were converted to 18-pounders while in the role of an ordinary field brigade with a division (IIRC 7th, 8th and 29th Divs), but they retained the RHA title. All three such brigades were converted to Army Horse (sic) Artillery Brigades, part of a general pool of field guns created in Jan 1917 by withdrawing one brigade from each division. They were V, XIV and XVI Bdes RHA.

Quick look at the LLT for Royal Horse Artillery and the Territorials;

Looks like the mainly the 2nd line batteries converted to RFA.

Western Front

126 Brigade RFA included 2/A Bty HAC and 2/1 Warwickshire Bty RHA

158 Brigade RFA included 2/1 Berkshire Bty RHA and 2/1 Shropshire Bty RHA

223 Brigade RFA included 2/1 Leicester Bty RHA

293 Brigade RFA included 1/1 Glamorgan Bty RHA

298 Brigade RFA included 2/1 Essex Bty RHA and 2/1 Hampshire Bty RHA

Middle East

263 Brigade RFA included 1/1 West Riding Bty RHA

India

215 Brigade RFA included 2/1 Nottingham Bty RHA

UK

297 Brigade RFA included 2/1 Glamorgan Bty RFA