Black Watch Regular Battalion buttons going into WW1

[red66ford]

Hello all. This is my first post so bear with me. I have been told that the BW Regular battalions would have begun the war with regimental buttons on their SD jackets. In fact one source said the 1st Battalion buttons would have had a 42 on them. I have also been told this was only true for SNCO and officers. So, does anyone have photographic or documentary evidence that proves which buttons they wore? My apologies if this has been covered before but I never have much luck searching forums. Thank you.