There are many architects London around so when looking for a good architect make sure you do your homework and research the different firms around. Some things to make sure you find out:
What projects have been worked on by the architects, commercial and residential. Word of mouth is always a great way to find a reputable company. Ask to view some of the projects they have worked on and speak to the consultants directly. You will soon get a good feel as to how good the company is.
We recently needed some commercial work undertaken and after spending many months researching different architects in London we found dblo associates to be the company that is the most recommended in the industry.