Strong Finish Book Editing Services



1000 +
Books Strong


First-class book editing services for thirty-five years: manuscript evaluation, substantive editing, line editing, copy editing, proofreading, and production support.

6 New Best-Sellers and
14 More Awards since 2020!


Serving Clients Worldwide

canada, USA, england,
france, switzerland,
netherlands, spain, china


(logos copyright of their publishers)
Alfred A. Knopf logo.
House of Anansi Press logo.
Doubleday book publishing logo.
HarperCollins logo.
Hogarth Press logo.
Hudson's Bay Company logo.
McClelland & Stewart logo.
Moody's logo.
Museum of Contemporary Art logo.
Nelson logo.
Orca Books logo.
Oxford University Press logo.
Pearson logo.
Penguin book publishing logo.
Penguin Random House logo.
Random House logo.
Saks Fifth Avenue logo.
Simon & Schuster logo.
Skip the Dishes logo.
VISA company logo.
Yale University logo.


Heather Sangster of Strong Finish has worked with internationally best-selling and award-winning author Margaret Atwood on 19 consecutive titles and counting.

Starting in 1995 with  the poetry collection Morning in the Burned House, Heather has copy edited and proofread not only Atwood’s poetry but also her non-fiction and fiction, including The Testaments, the 2019 Booker Prize–winning sequel to The Handmaid’s Tale.

Margaret Atwood is the recipient of multiple prestigious awards, including the Commonwealth Writers’ Prize, Giller Prize, and the National Book Critics and PEN Center USA Lifetime Achievement Awards. A number of her books have been adapted for film, television, and theatre.

“Many thanks are due to … Heather Sangster of Strong Finish, the demon copy editor who picks every nit, including those yet unhatched.”
~ Acknowledgements in The Testaments

“Heather Sangster has been the primary copy editor of my work for the past 28 years and my publications owe a great deal to her services. She is meticulously thorough and thoroughly professional.”
~ Margaret Atwood

Heather Sangster/Strong Finish in The Globe and Mail

Making the Right Calls

Strong Finish delivers high-calibre professional book editing services, including manuscript evaluation, substantive editing, line editing, copy editing, proofreading, copywriting and research, and production support.

A combination of classic principles, contemporary sensibilities, insider expertise, and just the right touch delivers a signature service with measurably superior results.

Whether you’re an author, publisher, or savvy business who needs book editing services or publishing advice, Strong Finish can surely help.

Book Editing Services

manuscript evaluation

Insightful analysis of your content and technique, along with effective suggestions and other added-value feedback.

substantive editing

A big-picture examination to shape structure, credibility, voice, message, and other fundamental elements.

line editing

A thorough line-by-line edit for style and beyond, to improve flow, tone, precision, and clarity.

copy editing

A rigorous review to correct mechanical issues (grammar, spelling, punctuation), check facts and consistency, and so much more.


A meticulous final read for quality control, checking for design/formatting consistencies, image/artwork placement, and any other lingering errors.

copywriting & research

Persuasive, natural copy that ignites action. A deep dive into fact-checking and supplementary analysis.

6 New Best-Selling Books

Portfolio Sample

Let’s Get You There

Your book—my advice—no strings attached. I’ll provide clarity and peace of mind by showing you next steps and pricing.