REBEL HONOR GUARD
There's not a lot to report on the Rebel Honor Guard since they only made a brief appearance in the closing scene of ANH.  But here's what I have so far...

The Helmet

The helmet appears to be identical to the helmet worn by the Rebel Fleet Trooper, with the exception that the dark visor has been inverted to cover the face.  For a more in depth discussion of this helmet, refer to the Rebel Fleer Trooper page.  

The Uniform

Thanks to Derek Lyons (the guard on the left) I can confirm that the uniform is an old British Army uniform.  I haven't confirmed which one, but will do some research soon.  The color is a uniform olive green.  Two flapped pockets are visible on the chest and two more are visible below the belt line.  

The Belt

The belt appears to be the same belt worn by the Rebel Technicians seen in the flight hangar on Yavin 4.  It appears to be an olive-drab canvas belt with a two-piece brass buckle.  I haven't tracked down the buckle yet, but will keep searching and post my findings here.  Given the military history behind most of the SW props, this is likely a British military belt used sometime between the 40's and the 70's.  

The Staff/Lance

The staff that the Rebel Honor Guard is holding seems to be a straight pole with a white or metallic knob on the end.  If the guys holding the staffs are of average height, then the staff would be about 9 to 10 feet long.  Although this staff appears to differ from the staff held by the RFT trooper at the guard post on Yavin, they seem similar and it suggests some connection between the two uniforms.  Maybe the Honor Guard is a elite corps or they wear a special dress uniform? 

Reference Images