Wall Unit Fitting Advice

We've been given a few base and wall units by someone having a new kitchen fitted, I'm fine with securing the bases but given the wall material / layout I'm a bit unsure on the best way to secure the wall units...

It's an 1930's house and at some point the downstairs bathroom has been taken out and a door / wall moved to leave an "extension" off the kitchen just under a metre wide and about 2m long. The metre wall is an exterior one that's been plaster-boarded over (dot and dab), the other has also been dot and dab'd but not sure what's underneath only that the consumer unit and all the wiring etc backs onto it from the other side...

As for the wall units they have a thin fibreboard back with a rough cut hole about the size of a decent coach bolt / screw in each corner - clearly worked in the past but not ideal?

My idea at the moment was to pad out the fibreboard to the depth of the frame by glueing some mdf spacers on the back, doing similar on the inside face and then using some coach bolts / screws with suitable plasterboard plugs to secure it. I could also apply some no nails or similar to the rear spacers so the units would be supported by both the fixings and adhesive.

I'm thinking the above would take some of the strain away from the thin backing and do the job, there aren't going to be piled hight with cans etc so would this suffice or is there a better way of doing it?

Thanks in advance

 

Thanks for the quick reply Got a feeling that whilst taking the photos I may have stumbled across the answer lol - got given four wall units, the two I checked at the time had holes only in each corner yet the other two having actually looked at them have metal corner plates on the inside ... typical... Attached is a photo showing them, unfortunately I cant get to one without as they are rather buried in the shed - sorry! The location and size of the holes look the same though so just a case of replacing the missing plates and using suitable fixings?

Thanks again.

 

Cheers - that'll teach me not to double check before making things far harder than they need be lol