So I know that editing and resaving a jpg will reduce the quallity and file size, but this was all done on's in lightroom so I know that's not the problem.
The photos were quite underexposed and so had a to be pushed a fair bit in LR to bring the up then exported the JPG at highest quality no size reduction.
I did an export using the same settings on the unedited 's and the difference in file size is around 6mb.
I think I'm sure that the more you push the processing the more you'll degrade IQ and consequently file size, but then I've been known to be wrong on occasions too (80's hair for example) so is anyone willing to shed some for me? I"d really appreciate it!