Programmer to prototype Web Application (London)

I'm afraid this isn't paid, but if this idea is successful a share of the business is on offer.

I'm in London and would prefer someone local.

I'm looking for someone with experience in an appropriate language to prototype a web based data visualization tool. Not sure what environment this would be in, I would need recommendations on this. So the person would need to have a broad skill set and be able to chose the right environment from PHP, Java, C/C++ ...

At the start this might just be a conversation around viability. I have a good concept of how I want this project to look, function and grow.

Anyone interested?