I've tried to create a couple of different effects, but it was also a chance to keep practicing how to use the adjustment brush in LR.
The first, I'm not so sure on. I wanted to try and bring out a face or two in the crowd to make them stand out with the Cenotaph, but I'm not really sure what I'm trying to create out of this image.
The second is one where I have tried for a "ghosts of the past effect" as there were some people there, as part of the service, dressed in period costume. It seemed appropriate to try and turn them into black & white. For this image, I think they are too far away to give it much impact.
The next ones were simple. I just dropped all the colour out apart from red (and a little blue in one) to make them stand out.