Moving external meter boxes

[Bill Williams]

Can these meters be moved to this position

(by Cadent / National Grid), or is there a rule that says they can't be on top of one another?
Is there some document that says this can be done....

 

[footprints]

Those are recessed boxes I would not think cutting the wall out that close to a corner would be a good idea, can't see any problem with stacking them though. It would of course be impossible to run the supplies directly up to them as one supply would have to pass the box below. Expensive job to move both too.
If it is because you are having an extension why not put them on the new front wall?