Hi Gavo,
While what Marcus points out is true (you can prompt local results for web design companies by adding 'in' to your query), it's important to understand that Google does not view web design companies as being truly local, hence their lack of inclusion in the results for the most common service + city or city + service queries. To my understanding, Google's thinking on this is that most web design (and SEO) companies operate virtually (don't meet with clients face-to-face).
So, you can add your web design company to Google's local index, and you can build citations for it, but it's likely that your overall organic rankings will hinge more on other forms of marketing in which you engage. Think content development, earning links, social outreach, etc.