This is the kind of cover letter which gets you an interview…
… a good interview gets you onto the shortlist…
.. and then a good cover email to say thank you get’s the job:

Hello again to you both,

Thank you for meeting with me today to discuss the Graphic Designer/Artworker position. I’m now even more enthusiastic about working with you both and everyone else at Wedo. I am also more convinced than ever that my skills in Photoshop and Product Retouching would be a strong match to be able to accomplish the challenges and issues that were discussed.
With your current backlog of product imagery that needs addressing i feel it would be the perfect opportunity to implement style guidelines, which will assist with quality assurance, keeping the imagery on brand and consistent. This is exactly the sort of challenge i am looking for and one i would conduct with great enthusiasm.

I also believe that my experience with Graphic Design, Illustration Animation, Still and Moving imagery would bring additional advantages if the business needs allowed for the position to develop further. It is exciting to see that the company has scope moving forward and for the visual elements to develop further, should the opportunity arise; my dedication, ideas and solutions would ensure that Wedo’s future visual identity is delivered to an exceptional level and exceeding expectations. I am really looking forward to discussing this with you again and look forward to hearing from you shortly.

Once again, many thanks.

Kind Regards

James Burton

It’s not hard
** Full disclosure: I sucked at this when I first started job hunting in London, so speak from both sides of the table!