Hi Robert
The first thing I would do is to get yourself some larger I mages for the slider for larger screens. You have done the medium size at 600 px width which to be honest should be your smallest then one around 900 px wide for medium and finally one of aruond 1900 px wide for the larger size.

And they can be jpeg rather than PNG.

I seem to have it working now. Only the logo is a png - the slider images are jpegs and they will only be for small screens. Thanks again.

I am not sure I understand about showing for smaller screens. Are you hiding the slider on larger screens?

That is the plan and have a video playing from 800px+. Can I do that?
I was thinking about loading times/sizes and preferences of Google with mobile versus desktop.
May need a rethink if not possible.

Sure that's possible but for loading times and users bandwidths qouta for those that don't have unlimited quota then the video would be best if it was online rather than within the resources foldera