FB.
Whilst I am no Labour/Corbyn apologist just a couple of points.
The first year of Blair's Govt saw defence expenditure as a proportion of GDP rise from 2.3% to 2.5%. It averaged around the 2.3% mark until Cameron came to power and it now sits at 2% after he decided to include pensions and other misc costs in the figures which weren't included pre 2010.
The article in the DM refers to a satirical pamphlet written by Daniel Cullen (Not the RAF Pilot awarded the DFC). It was written during the Afghan conflict in conjunction with 'veterans for peace' to protest against that war. Proceeds were donated to military charities. I can only assume some members of momentum had some copies still or the DM was playing a bit fast and lose with the facts for political gain.