Help Needed Identifying a Uniform

[JSB]

Hi everyone.

I am a complete novice to this site, looking for some help identifying a uniform and cap badge/regiment if that is possible.

Attached is a picture of a chap wearing, what appears to my untrained eye, a military uniform, possibly circa WW1?

So, what do I know about this chap? In short, very little!! He is possibly my Great Aunt's illegitimate son (in which case the uniform is likely to be closer to WW2), or her fancy man who assisted the production of her son

Either way, she managed to keep this rather dashing looking chap a secret from the majority of the family for the greater part of 70 years.
In fact, he only came to light upon her death in 1990, at the grand old age of 95, when her younger sister blurted out "Who is going to tell her son?", walked over to a picture to of me and my brother, opened the back and out popped a photo of this chap........enter complete surprise and stunned silence from the whole family!!

As I mentioned above, very little is known about him as a person and my military knowledge is pretty thin (I am not even sure this is a military uniform) hence my request for some assistance. For info, this is the only photo that exists of him in our family.

If anyone can shed some light on the subject, I will be very grateful.
Thanks
Jules