My reason for not doing it was that I am a self employed IT contractor currently required on a 24x7 on-call basis according to the terms of my contract and that I have no backup staff.
This is serious, because my current contract could be in jeopardy if I cannot meet the terms and conditions of the contract.
But, they rejected my reasons.
This is very bad for me.
Sure, if i was in a cushy full-time job I'd not mind it. But, this is a disaster for my employement as I'm also in a highly specialised area where there has only been one other job advertised in the last year. So, it is a case, do jury service, and maybe lose my job, or just don't turn up and get thrown in prison.