That Yellow thing is a sirus based on the lugs they used but a rare one with a 24" front wheel.
This is a poor copycat of the famous Martin Pyne mini bike.
I posted details of this bike on the Timetrialling Forum and got the same answer from Nob, which was helpful in that it does seem to identify it as a Sirius, but I'm still curious as to why it is a "poor copycat". This is not an annoyed response, I am genuinely puzzled as the photo I posted surely doesn't give enough info to indicate that it's a poor bike. A copycat I'd agree but it's reasonably light, stiff and rides very well now that I've more or less got it finished - although it's the nature of these things that I'll keep changing bits until I either reach my own limits of improvement or move on to something else.
I've shown the current version below, I rode it like this in my first tt for over 30 years, only 5 miles but great fun with a fine bunch of folks. Results aren't out yet but I understand I did 15:27, which was reasonable for someone of my age (57) and limited experience, considering the very windy conditions and a course that is far from flat. The computer is on it just for me to get some data on how I'm doing, I'll take it off for an event and I took the tri bars off as they were too low and I couldn't get on with them. One of the senior guys at the tt has pointed me towards some tri bars that have risers under the forearm pads to get some height so I might try them. The riding position as it is now is very comfortable, rather like being down on deep drops on my current road bikes. The only gripe is that the shifter is not ideal, I'm not keen on taking a hand off the bars at speed so I'm looking to sort out a bar end shifter that should makes things easier and safer.