Expanding on the BNA references,

Gloucester Journal - Saturday 04 September 1937

FOREST MINERS’ CHOIR
The musical miners of the Forest of Dean will be on the air Friday, September 24. Cinderford Male Voice Choir has been engaged to broadcast from 8.10 p.m. to 8.50 p.m. on that date, from the Bristol Studio………………………………………..Mr Harry Dobbs has been conductor ever since the choir was founded, 25 years ago, and the success of the organisation is a great tribute to him.

Gloucester Journal - Saturday 08 March 1913

………. the second annual concert of the Cinderford Male Voice Choir – Conductor Mr H. Dobbs……….

These imply the choir was founded c1912 but I wonder if it was the revival of an earlier choir,

Gloucester Journal - Saturday 03 August 1901

The Cinderford Male Voice Choir performed, under Mr W. M. Everett, at Littledean cottage garden and vegetable show.

Gloucester Journal - Saturday 16 August 1902

at the Cinderford 9th annual flower fruit and vegetable show under Mr. George Kear.

Gloucester Journal - Saturday 07 May 1904
at the 7th Forest of Dean Eisteddfod under Mr. W. M. Everett.

Gloucestershire Echo - Saturday 13 July 1907

at the Ruardean Band Contest under Mr. G. Kear.

Gloucester Citizen - Friday 23 August 1907

at Cinderford Town Hall under Mr George Kear.

The earliest reference to a broadcast by the choir I can find is,

Gloucester Journal - Saturday 22 October 1932

CINDERFORD CONCERT The Miners’ Welfare Hall at Cinderford was filled last evening, when the Cinderford Male Voice Choir gave their Autumnal broadcast concert…………………
…………………..The items of the programme, which were broadcast from the West Regional Station, Cardiff, were…………………