Two mentions for a ‘R.H. Hamblyn’ show up in the Military Ancestors Database.
The first was published in the Bromley & District Times on the 14th August 1914 (page 5), for a R.H. Hamblyn of Bromley in the Territorials.
The second in the same publication on the 4th September 1914 (page 2) for a R.H. Hamblyn, member of the District Times office (Bromley Printing Dept.) and serving in the 5th Battalion, Royal West Kent Regiment.