If a private booking is made with a hotel for a given period for at an agreed price, say ten days for a thousand pounds and circumstances require you have to leave before that period is over, what is the usual (and legal) position for payment, are you normally expected to pay the full amount?
It depends where the hotel is. In the UK I think that the hotel is obliged to make clear what its cancellation policy is, if there is to be a charge. If no cancellation policy has been provided, I would think the norm is to charge for the first night of cancellation, plus any discount that may have been given on the nights taken due to the length of stay.
there may be no hard and fast rule, regulation or law to cover this except that the booking in its original form will be regarded as a contract, especially as soon as any payment is made or security (e.g. card details) is made. Some hotels may/will charge only for the period used, especially those who have no difficulty filling the accommodation for the remainder, others will insist on charging you for this also.
It depends on if its your circumstances forcing you to leave - therefore I would imagine you would have to pay in full.
If its the hotels fault that you had to leave early then some form of compensation would be due to you.
As said the t&c and cancellation policy is what should happen.
Mind you if you book say a 5 night break with the usual price at £100 a night (£500) but by booking 5 nights you get a 25% discount (£400) and then leave early you would (again depending on &c) be expected to pay £100 for the nights you stay.
If your stay is shortened by an emergency, you might have a valid claim on your travel insurance for any nights which you paid for but did not spend in the hotel.