Just seen this on Flickr and thought the axle set up looked odd, are there many of these about?
Perrys of Gobowen Renault Premium by Scammell Amazon, on Flickr
theres a 4 series scanny that knocks about on the m62 corridor simillar to that never seen the thing sat still to get a piccy though 
The extra axle will carry the weight of the crane so they can still load the trailers heavy at the front. Although the crane doesn’t look enormous so it will have a low payload compared to a standard 6x2 unit.
Obviously it makes sense to someone.
I saw a bin wagon the other week, its the first one I’ve seen with tri-axles at the back. It was a bit far away but it looked like the standard 3 axle set up (1 at the front 2 at the rear), with an extra mid-lift axle at the rear. It wasn’t overly large , just looked like a standard size bin wagon. This was in Bolton.
Tarrman:
I saw a bin wagon the other week, its the first one I’ve seen with tri-axles at the back. It was a bit far away but it looked like the standard 3 axle set up (1 at the front 2 at the rear), with an extra mid-lift axle at the rear. It wasn’t overly large , just looked like a standard size bin wagon. This was in Bolton.
tridem set up is coming through and supposed to be easier to drive and turn round 
tri drive redi mix trucks do not like being off road ,you would think no problem just power though the muck!
unfortunately you cant stear the ■■■■ things in the muck ,still prefer normal 8 wheeler redi mix but wi 2nd steer axle driven.
jimmy
Worryingly to me too 8 wheels.
And I think your spot on. Not sure how workable though
Looks as though the crane is about 40t and would weigh about 5 ton. The truck is a cheap 6x2 push axle bog standard fleet truck. The front axle may have been uprated or its just had the wheels fit to look the part. Then a tag axle conversion.
The name escapes me but there a firm at Tingley that have something similar for shifting empty 40 foots (Simsons)
But to try and use for bulk on general will surly nack it. The weight of the axle and crane must be 5 ½ ton
Its weight that eats the fuel, and when your running at 20t empty and only having a payload of 24 ton at 44t don’t seem to stack up
Having said that if you get 3 days a week at that and a couple running a specialised operation like setting the 40 foots I dare say that’s far more profitable than running a basic motor on bulkers all week.
I like to see something out of the ordinary anyhow so it has my vote.
I also love to motors that are given a second chance to make a living.
there’s a scanny tridem for sale on the scanny uk website.