I just discovered that Brock Clarke's excellent article on Muriel Spark in this month's issue of The Believer is available online, and so hastened here to direct you to it.
I'm a huge admirer of Muriel Spark's work in general and of her first novel, The Comforters, in particular. And I've long thought that Spark's innovation as a metafictionist has been unjustly overlooked. Imagine my pleasure then to stumble upon Clarke's article and find him lauding that very aspect of Spark's work with a particular focus on The Comforters as well as the novel which followed it, Memento Mori.
Click here to read Clarke's article. I hope that it will pique your interest in The Comforters if you haven't already read it.
(Note: The image above is a portrait of Muriel Spark painted by Alexander (Sandy) Moffat in 1984 which is owned by the National Gallery of Scotland. For more information on it, click here.)