Very close. Definitely Gunter out front in 1977 at Puncture Park (aka ACUSA Park, Harrogate, at the inaugural Hang Ten Championships).
There was a third Honda rider on the 250 with the Mugen kit and HRC front forks (gas bottles extending up above the top triple clamp). #16 is Willoughby. Rowlands was #3, not #4 (at far left).
Maybe #22 was Riley, who tragically died after a fall in Mr MX at Broadford in 1979 (or 1980)