Hi Chris, I tried OTA and then resorted to iTunes. The update is finally complete.
To answer as to why 1.80GB is large - Perhaps because we are in South Africa where the luxury of decent bandwidth is scarce - I am however on a good line. To wait over an hour for a single update (we have 4 devices in the home) is not convenient.
When updating OTA there seems to be no progress indication - a turning cog means very little if you have no idea when it will end.
The update stated it was 85MB yet it turned out to be double.
Perhaps if one could see that something was actually happening when updating OTA it would not be quite as frustrating.
Anyhow, I apologise for posting to a user forum. There is nothing anyone can help with.
Thank you for your response tho. Much appreciated.
[ I think I am highly irritated as I updated to El Capitan and find that my machines performance is almost halved. I cant revert back to Yosemite. This process took 3 download attempts. ]