This does appear to be a Squadron. There are three guidons visible in the picture which indicates three troops, the right number for a Squadron. In the first rank is the Squadron Commanding Officer (CO) (on the gray horse). To his right is the Troop CO and to his right is the troop guidon. To the guidon's right is the first platoon, with the Platoon Leader centered in front of them and the platoon sergeant in file behind the rightmost member of the platoon. After an interval, there is the second platoon (only 7 men!), with the Platoon Leader centered in front, and the platoon sergeant behind, this time, the leftmost file.
Another interval, and the second troop, with the Troop CO to the left of the guidon, the first platoon to the right with the Platoon Leader centered in front and the Platoon Sergeant (also on a gray horse) behind the leftmost file.
Farther back is the third (and much larger) troop with the Troop CO on the left of the guidon and the rest of the troop behind.
It's a full Squadron, but a badly under strength one.