Not as far as I am aware regarding roof tiles blowing down. The building is in a very poor state of repair and is very old. It has had no maintainance for several years. The building isn`t secure and is open to the elements. The lady has been advised in writing that it`s condition is dangerous.
In a very old case called Nugent v Smith (1876) the Court defined ‘An Act of God’ as: "Natural causes directly and exclusively without human intervention…could not have been prevented by any amount of foresight pains and care reasonably to have been expected”. In simple terms an Act of God can be relied on where a natural cause has resulted in loss or damage and could not have been anticipated.
Where the occupier has taken no steps to keep the property in good order and this has result in tiles coming loose, I think there is a strong argument to say this is not an Act of God. Had the property been maintained there is an argument to say the tiles would not have come loose. I think you should go back to her and say that you reject her defence and wish to pursue your claim. If she has any sense she will negotiate and acceptable settlement otherwise you will have to take the matter to Court.
Can I assist further?