I remember clambering around inside a Saracen at a Leuchars air show when I was a kid and ever since I’ve rather liked them.
What happened to this one’s turret? I think that Saracens usually had a little turret for their MG, not a cupola.
A bit of Googling suggests that this is in fact the FV 604 Regimental Armoured Command Vehicle, rather than a standard FV 603 Saracen APC. Some FV 604s had turrets and some did not, plus they had different roofs to the standard APCs (those flangey parts aren’t there on the APC) and extra storage (possibly for pigeons, if maccruiskeen is to be believed).