What mark Firefly?

[TColvin]

Can anyone tell whether this is a Sherman IC (M4 17pr) or a VC (M4A4 17pr)?
And if so, how?

As background, it is the leading tank of a demonstration in force by 2 Polish Armoured Regiment, 10 Polish Armoured Brigade, 1 Polish Armoured Division, 2 Canadian Corps on May 7, 1945 in the town of Wilhelmshaven.

And can anyone identify the box attached above the unit sign (white 52 on red background). I note a spare road wheel mounted on each fender.

The photo was taken by Christopher J. Woods, and the negative is PA152508 of the National Archives of Canada.

Appreciate your help.