We managed to work out the cause of the problem. It was the Windows 10 Anniversary update coming down to our laptops. We had setup Windows 10 to send updates to PCs on my local network thinking that it would download once and then distribute to other computers on the network. It turns out we were totally bogged down and we have had to turn off this option. It is a shame as given we are on a very slow link this option had it worked would be ideal for us.