Wonder if this is just this set: LINK with added masks. Would be nice if they were completely new posed figures, but probably are not.

I doubt it, as the figures you posted are the 1914 issue uniforms, and the gas mask figure is of the later uniform. However, ICM has indeed been molding thier later uniformed figures as "gas mask" sets by including the heads with gas masks. I recently purchased thier Late war German Infanty with gas mask, only to discover they had previously issued the same set without the masks earlier. They've also announced late war French and US troops with gas masks as well. But, there is an entirely different set of 1914 uniforms for French, German, Russian and British troops (which is the one you depicted) that would not be suitable for the gas mask issues. By my count, ICM has several WWI Infantry sets out now, at least 2 French Infantry sets, 3 British Infantry sets, 3 German Infantry sets, 3 US infantry sets, 2 Russian sets, 1 Turkish set, with several more in production. These sets range form early War to late war uniforms. There are several combination sets too. VR, Russ

The Box art photo looks exactly like the Andrea Miniatures 1:32 British soldier (soft metal)

If the only obvious difference is the leather jerkin, with different heads, these guys could be mixed up with the previous set for a larger group. Throw in Tamiya's figures, which are also very good, but a bit smaller, and you have a real assault going on.