As predicted...

...Steve's just made a last minute change to tomorrow's grocery order which meant taking two of my bottles of pop off so that he could have meat, so the final totals now look like this:

My stuff:  £3.54
Steve's stuff:  £24.31
Joint stuff:  £18.15

So, as is normal, Steve's stuff is significantly more expensive than my stuff and the joint stuff all bundled in together and over £20 more expensive than my stuff alone.

I dunno why I thought this week would be different, I really don't 😞