The 'Great Western Railway Magazine' had this article in the October 1904 issue, written by James C Inglis, the GWR's General Manager.
There was a follow-up article in 1905.
Some opening dates:
Honeybourne - Broadway on 1 August 1904.
Broadway - Toddington Goods on 1 August 1904; Passenger on 1 December 1904.
Toddington - Winchcombe on 1 February 1905.
Winchcombe - Bishop's Cleeve on 2 June 1906.
Cheltenham Malvern Road station opened 30 March 1908 (for trains to and from St James).
Line opened for through traffic on 1 July 1908.
A few relevant snippets from the 'Cheltenham Chronicle' :
The first sod for the new line was cut at the Cheltenham end in November 1904 on the old Workhouse garden.
At Malvern Road station and yard, a steam navvy finished work at the end of 1906 after three months excavating 65,000 cubic yards of earth 'including the big bank on the Gloucester Road side.'
Arrangements for signalling in and out of Malvern Road locomotive shed were inspected on Monday 14 January 1907 with, in attendance, among others, Mr W A Stanier, Divisional Locomotive Superintendent. Erection of Malvern Road West Signal Box will follow in due course.
Malvern Road station island platform is now built, but the contract for the buildings - to be in red brick with blue facings - has not yet been let.
From the early 1950s 'The Cornishman' was the Honeybourne line's named train.
This timetable was in operation between 15 September 1958 and 14 June 1959.
The call at Gloucester was Eastgate station, the ex-Midland one, not the GWR's Central, and
its route into Bristol was the ex-Midland line via Mangotsfield.
During the summer, the train ran in two or more parts on some days, but tended not to have the name on Saturdays.