As others have said, it's an Old Crow model, specifically the 25mm scale Sabre Assault Tank (note the same tank was made in 15mm scale too!). It has had various extra elements added to it as well, which look to be a mixture of Old Crow accessories (fuel barrels, towing hooks, secondary turret mounted on the main turret, tank hatches, and replacement main gun barrel taken from the Halberd Assault Tank), scale model add-ons (Jerry cans, towing cable), and hand-sculpts that are likely to be garage kit resin items (rolled-up camo net and other soft stowage).
Like Ragsta, I was under the impression that a the owner (Jez Plumridge) had essentially closed, but still had the whole setup; so polite and patient email or two may yield some success and Jez can one can be cast up for you.
The full vehicle can be seen here, as the shots you reference in the book are all sadly partials:
https://zacgaming.wordpress.com/2010/11/30/old-crow-vehicles/And here's a thumbnail I found of the whole tank Kevin Dallimore painted:
Also, whilst in the subject, there's a few more Old Crow vehicles in the book:
Page 43 -
Wheeled Gecko Scout, with an additional missile launcher taken from the 25mm Missile Turret accessories pack. It also has a hand-sculpted/garage kit rolled-up tarpaulin on the hood, and a painted bead/round-head pin on the roof for a comms/sensor device.
Page 139 -
Wheeled Outrider Scout Vehicle. The turret it a Tank Turret from the 25mm accessories pack, and the turret hatch is also an 25mm accessories pack. The rolled-up tarpaulin is a hand-sculpted/garage kit part as above, and there are various plasticard add-on greebles too, including the exhausts which also have some aluminium body mesh wrapped around them. It has painted bead/round-head pins on the front for a comms/sensor devices. Finally, the missiles look like they might be cut-down from Tac Missile Turret 25mm accessories pack.
Page 153 -
Dragoon Half Track. Visible accessories include scale model jerry can on the hood, and plasticard for additional front hull armour and wheel arch-mounted number plate. Modeller's chain (probably from the Old Crow 25mm accessories range) on the front bumper. The turret isn't visible, but from
this pic I found, it looks to be the standard turret that comes with the vehicle.
Finally, not in the book, but it looks like more the Kev D tanks can be found on the Hammer's Slammers site
here. Pics of the Neo-Sov vehicles
here, and the "Western" Mercenaries
here.
I hope that's of help, and even if you can't get hold of any original Old Crow vehicles, at least the above should help you kit-bash some close approximations!
///Edit: Whilst the Sabre Assault Tank on the Old Crow site doesn't show it, it's quite possible that there were turret options available at checkout, or even included as extra in the boxed kit - so the main gun (visible on the Halberd Assault Tank) may have been an "original" part of the kit, as seen on the blog I linked to above.///