If I'm called up for jury service will I be able to claim for my lost/delayed holiday?

Yes. This is called cancellation cover - and, providing the cancellation was beyond your control - such as compulsory jury service, then, as long as you did not know about the jury service at the time of booking your trip or insurance (whichever is later) you would be eligible to submit a claim. The same cover applies if you were unable to go on holiday because of illness of a member of the party travelling with you or the serious illness or death of a close family member. However, if an urgent business appointment came up that would not qualify for reimbursement.