Recommended graphics agencies?

Hi everyone,

My company is looking for a graphics design agency to provide visual design concepts (color scheme, iconography, styling, aesthetics, etc) for an enterprise product. We have an in-house UX team who is responsible for use case analysis, low-fi and hi-fi mockups. It is important we find someone who can work within the boundaries of our design to create an elegant/polished look & feel that can be applied consistently throughout the product.

Does anyone have any recommendations for graphics designers/agencies in the London or surrounding areas?

Thanks!

Joe