Thanks for the post.

We are currently adding to our directory of services and shops in London, but for the time being we do have a listing for Chapmans in Islington: www.thegoodwardrobe.com/chapmans

In the next couple of weeks we aim to introduce a review facility on the site so if you do have your machine serviced there, please do let us know how you get on by posting a review.

Good luck with the service.

Sew Amazing on Roman Road is a great family business, and IMHO best in terms of both service and price. Call first to check they're not out on service visits.
http://www.sewamazingltd.co.uk/

If you can get there, I'd go to to Chapmans in Camden, who are also industry favourites. http://chapmansewingmachines.yolasite.com/

Thanks so much for those recommendations, I'll check them out. In the meantime, just today I found Let's Learn in the Grand Arcade in North Finchley, offering sewing machine servicing, classes, alterations and pattern cutting, so adding them in to the mix!