I think it's a wonderful photograph! Sharpness is desirable but overrated. Grab shots rarely are critically sharp. The spirit of the composition is more important, and this photo has spirit. Imagine if your father had been obsessed with sharpness. He would have mounted his Voigtlander camera on a tripod, attached a cable release, stopped down the lens to f/5.6 or f/8 -- and missed the moment with the laughing policeman. Or the policeman would be even less sharp because of the slower shutter speed required to stop down the lens. Many years ago I took a picture of this same scene (the Arc de Triomphe in Paris) with a Leica. It's sharper than your father's picture but not as good, because it doesn't include a laughing policeman. That said, your photo can be improved. Your digital copy is filthy. Unless the dust is embedded, you can remove it before making another copy. Before I copy a slide or negative, I shoot both sides with an anti-static gun, brush both sides with an anti-static brush, and finally blast both sides with a rubber squeeze blower. Also, the picture still looks too blue to me, despite your color correction. A quick way to correct old slides is to find a middle-gray part of the picture and click it with the mid-tone eyedropper in the histogram tool. Adobe Photoshop and most other image editors have these eyedroppers. The leftmost eyedropper sets the black point, the rightmost one sets the white point, and the middle one sets the midpoint. In a color image, it also adjusts all the colors to align with the middle-gray area you have clicked on. There's lots of concrete in your picture, so you can easily find something that should be middle gray. You may need a few tries to find the best one. Below is my quick adjustment using the mid-tone eyedropper. I also reduced the yellow saturation slightly and applied some sharpening. (Unrelated, I downsized the resolution for faster uploading.) My version can be further improved by someone with better color perception than mine, but the main point is that my corrections took only a few seconds.