I agree with Kobunite, but by a different route. I can't make out the cap badge well enough to identify it positively, but the collar badges are either Royal Artillery or Royal Engineers, which are quite similar. The cap badge definitely isn't Royal Artillery, which looks like this:
So he's Royal Engineers. The uniform is that of a commissioned officer: the diagonal strap is part of a "Sam Browne" belt, which were only worn by officers in the British Army.
The rank insignia would be on the jacket sleeves (until 1920), and we can't see them. Several things indicate the subject is likely a newly-commissioned officer, including his age, the poor fit of the uniform around the shoulders showing that it is not tailored for him, and the lack of any decorations or campaign ribbons. So he's probably a Second Lieutenant, the starting rank for officers. The style of the photograph looks like the ones that soldiers often had taken to send to relatives, but that's an impression, rather than hard fact.
It's very plausible that any one with a B.Sc. in an engineering-related subject would be commissioned in the Royal Engineers during WWI.