The Tannoy Kingdom Royal has NO MIDRANGE driver contrary to what you seemed to allude to.700 Hz wavelength is over 19" long, so a 12" driver wouldn't even be close to beaming. Tannoy knows what they're doing, but apparently you refuse to catch on, even with multiple corroborating explanations.
Their new HF compression driver tweeter is doing all the midrange.
Like you seemed to indicate - Tannoy is not foolish & they wouldn't put a 12" midrange! The 12" unit does upper bass to 700Hz & the lower bass unit does the bottom-most octave.
Fool that I am, I'll give it one more go:
In the '70s I owned a pair of Altec-Lansing 9845a professional studio monitors. They had the typical Voice of the Theater (VOTT) components--15" woofer and compression-driven aluminum horn. Around that same time I worked at a stereo store where we carried Altec, including some home versions of the VOTT.
But they sounded significantly different. My pro audio VOTT crossed over at 500 Hz, which is a 27" wavelength and well outside the beaming frequency (900 Hz) of a 15" wavelength. The home version, however, crossed over at 1200 Hz, which is an 11" wavelength. That means that *that* 15" woofer was beaming from 900 Hz on up past the 1200 Hz crossover frequency. And you could hear the difference--a kind of "cupped hands" coloration in the crossover frequency area.
I think the difference in crossover frequency was due to the pro version having a better, more expensive and rugged compression driver that could play lower. The cheaper home version crossed over at 1200 Hz for power handling. These days, no one in their right mind would cross over a 15" woofer that high without a wave guide, whizzer cone, or at least a phase plug.
Unaware at the time about beaming, dispersion, and in-room power response, we typically figured that the horn was making the music sound horn-like. Yet my pro monitors had no such coloration (in fact, they kicked ass!). I also found that this suckout wasn't very noticeable when playing jazz combos and larger scale instrumental music, but was immediately noticeable on solo voice. From that point on--as much as I like instrumental music--I can't consider a speaker without hearing what it does with vocals.
So there's a little more anecdotal evidence for the impact of beaming on an inappropriate crossover point.