Time expired soldiers in 1WW

[CNB]

My great Uncle was with the 5th Battalion. Having signed up for 6 years in 1910, he was sent to war at the end of 1914.

He was sent home (for no known health reason) in 1917 and joined a munitions factory under W Class Army Reserve. This raises many questions

1. Did he ask to be released?
2. Was he released automatically because he was time expired? If so why did he stay on another year?
3. Why on earth would the army release an experienced soldier when other men were being conscripted for the duration? It does not seem to make much sense to me
4. Because he served beyond his 6 years - it seems he was entitled to a bounty and wrote to Norton barracks for it. Seemingly it was for £20 and N.B .gave him £5, he then, presumably had to wait for the rest. Does anyone know about bounties?

I would be grateful to hear from anyone who can cast light on these points, or add other points to consider!!
Thank you
cnb

[LarsA]

This note on the "W" reserve may be helpful.
Kind regards,
Lars

Class W Reserve and its Territorial Force equivalent Class W(T) were introduced in June 16 by Army Order 203/16. They were ‘for all those soldiers whose services are deemed to be more valuable to the country in civil rather than military employment’. Men in these classes were to receive no emoluments from army funds and were not to wear uniform. They were liable at any time to be recalled to the colours. From the time a man was transferred to Class W, until being recalled to the Colours, he was not subject to military discipline.