Thankfully, my neighbour and friend, Andrew, came to the rescue and was able to change the tyre for me. I am very glad we had already discussed and looked at the spare tyre prior to actually getting the flat, so the spare is perfect.

It might even be better to get a cheaper second hand tyre as the spare and continue using the one that is on my car now.

It does appear that a screw may be the reason for the flat.