Help with uniform identification

[alan o]

He is probably in the Army Service Corps.

This si the tunic  https://www.bing.com/images/search?view=detailV2&ccid=dtbwlJ5w&id=2060FC84B31785E3D670F09F329C3928511E74E7&thid=OIP.dtbwlJ5wtL5hZE7U8cGXVQAAAA&mediaurl=https%3a%2f%2fi.pinimg.com%2foriginals%2fa1%2f5f%2f39%2fa15f390e3aaa7a2a31c04ab3980fbf32.jpg&exph=500&expw=332&q=uniform+army+service+corps&simid=608006929045130656&selectedIndex=0&cbir=sbi&ajaxhist=0

The Austrian Knots on the cuffs  were not worn by the infantry and the design of the jacket is wrong for cavalry.  The East Yorks had a white backing behind their cap abdge so you can rule that one out.

As stated the "Brodrick" cap was in use from 1902-06.

[Ruskie]

I don't know if it is of significance, but the lace/braid (sorry I do not know correct terminology) on the sleeves is a different pattern.

What do you make of the cap badge Alan?

[alan o]

The lace is an "Austrian knot' and is as worn by the ASC. 

The cavalry's cuffs were more ornate whilst the infantry were a solid shape with a straight edged 'jam pot' cuff which later changed to a pointed cuff but again solid.

The cap badge is that of the ASC as this one:

https://www.bing.com/images/search?view=detailV2&ccid=akc6D0eZ&id=A5A0B7EC966669EBA7CA51BA8CCFAD11977A3163&thid=OIP.akc6D0eZ5PvCtKenXRWaYAHaHa&mediaurl=http%3a%2f%2fbritishmilitarybadges.e2ecdn.co.uk%2fProducts%2fFilenameaz787844099_4.jpg%3fw%3d547%26h%3d547%26quality%3d85%26scale%3dcanvas&exph=547&expw=547&q=evii+army+service+corps++badge&simid=607993245277032043&selectedIndex=7&cbir=sbi&ajaxhist=0

[Ruskie]

Though the badge in the photo is indistinct, the ASC badge looks to be a good fit shape wise.
Interesting about the cuffs too.