Hello Nigel,
First of all thank you so much for inviting me on your project.
Just I want to share some ideas for your logos I hope you don't mind?
The brief is clear to me but 2 points in the end of the brief will male your logo something messy look in your design.

"Also a chart showing an increasing graph that dips and rises like the MedX exercise machines developed by Arthur Jones.
Incorporating the nautilus shell is another option as shown in the picture supplied (ignore the writing on top please)"

So firstly I will execute it my way (Again I hope you don's mind?) and then we will discuss it in details for the design.
As this I'm saying because to make a logo for your firm more simple,descent, corporate, scientific, technical (as you want)

Thanks
With Regards
Amit Rohara

Yes you are free to do what you consider right with the design and thanks for your quick response and input.
Regards
Nigel

You are welcome and thank you for your reply also.
I will be soon executing the design with my concept.

Thanks once again
Amit Rohara

Thank you Nigel for the invite, I look forward to working on your logo.
I thin I understand what you might be looking for by your description, I put a lot of thought and experience into designing logos that portray what your about to the eye, quickly and easily, I will incorporate some of your imagery ideas, and please feel free to comment on my designs, I'm always very open to making changes if needed.
I'll send them soon
thanks!
ezra