In my review article here on Oliver Kamm’s recent book, I regretted its lack of references to non-prescriptive sources on the English language, and hinted that I would try to provide some suggestions.

This is the first of two articles which cover this area. The second will cover the major reference grammars such as the redoubtable Huddleston and Pullum: this article covers some books intended for more general use, including style guides and student grammars. With so many books on the market, I am only able to cover a personal selection, but hope that it will prove useful.

Style Guides

Oliver Kamm (2015) Accidence will Happen: The Non-Pedantic Guide to English Usage, Weidenfeld & Nicolson. ISBN 978 0 297 87193 4.
Reviewed in detail here. Strongly recommended as a first, and perhaps your only, style guide.

Merriam-Webster Inc. (1994) Merriam-Webster’s Dictionary of English Usage, Merriam-Webster. ISBN 978 0 87779 132 4.
This is about as non-prescriptive as this type of dictionary gets. Although it is now over 20 years old, and based largely on American English usage, it is an excellent and very extensive guide (over 2300 entries on almost a thousand pages) to good style which savages its prescriptive counterparts such as Strunk and White. It is also notable for using Otto Jespersen as one of its authorities on earlier usage. A good addition to the reference shelf, and always an interesting read.

Of Largely Historical Interest

Otto Jespersen (1933) Essentials of English Grammar, Routledge. ISBN 0 415 10440 8.
Despite its age and its idiosyncratic terminology, this remains an excellent concise summary of Jespersen’s 7-volume grammar, presented in more didactic form (but still non-prescriptive). It manages a surprising range of quotations, and finds space for ‘modern’ topics such as ‘weather it’, singular they, and much more. However it inevitably lacks coverage of changes since original publication, and is emphatically British English.

For ‘Native’ English Speakers

Harry Ritchie (2014) English for the Natives. Discover the Grammar You Don’t Know You Know, John Murray. ISBN 978 1 84854 837 4.
Aimed at those whose first language is English, this little book aspires to turn their feel for the language into more formal grammatical understanding. It does contain some excellent material, and should dispel any confusion over issues such as what is a passive, and tries to avoid prescriptivism. It could be a useful bridge for those wanting to move up to more substantial grammars, but its biggest weakness is its lack of an index, which makes it less accessible than it needs to be. I suggest that you look at it before deciding whether it will help you.

Student Grammars

Bas Aarts (2011) Oxford Modern English Grammar, Oxford UP. ISBN 978 0 19 953319 0.
This book appears modest, if not paling against the other grammars, but once you start reading it, you will see how good, powerful, and extensive it is. Divided into three main parts, it deals in turn with word formation and the basics of grammar, phrase and clause patterns (the core), and grammar and meaning including tense, aspect and mood. Examples are taken from its corpus base, UCL’s ICE-GB (with detailed citations of material used), and covers both British and American English.
Syntactic trees are used to present structure throughout. My only dislike about its layout is that all tables are set in shaded boxes, which I find irritating and anyone with impaired vision could find impossible. Although there is a great deal of information here, Aarts is very skilled at presenting it in a clear and understandable way, and this is probably the best taught of all these student grammars as a result. There are no exercises, but an appendix of irregular verbs with their past tense and participle, supplementary notes and suggestions for further reading, and a short but excellent list of references. It also has two indexes, one for subjects and the other a lexical index, providing excellent access straight to its content.
I really like Aarts’ approach, and the way in which he has made his understanding so accessible, and recommend you at least look at this.

Douglas Biber, Susan Conrad, Geoffrey Leech (2002) Longman Student Grammar of Spoken and Written English, Longman. ISBN 0 582 23726 2.
This is the student lead-in to the Longman reference grammar, and adopts a similar approach with the same corpus (Longman’s LSWE Corpus) base, which includes both British and American English, written and oral sources. This is quite different from other grammars, and you may love its frequent histograms showing usage frequencies from the corpus, or they may be distracting. Like its reference sibling, it also makes clear distinctions between different registers, particularly conversational English, to which the final chapter is devoted.
It is also very pedagogical, and laid out using dingbats, highlighting, and other devices to support that. Chapters are divided into ‘grammar bites’ rather than sections, which may appeal to those brought up on less traditional texts. However it does not offer any exercises. This is almost as comprehensive as its reference sibling, with nearly 500 pages which are dense in fact and content. It has a full glossary, and a list of irregular verbs with their past tense and participle, giving it a more prescriptive air. The index is very detailed, but there is no bibliography or list of references.
This is an excellent advanced student grammar for those wanting to perfect English as a second language, or who are going on to study English at a higher level. Its corpus base is valuable, and distinctive.

Kersti Börjars and Kate Burridge (2010) Introducing English Grammar, 2nd edn, Hodder Education. ISBN 978 1 444 10987 0.
This is aimed at students who are going to study English syntax or grammar at university, particularly in Australia, as it contains plentiful references to Australian English. It is strong on a modern syntactic approach, with useful coverage of non-standard English including electronic and regional forms (Indian). The text engages the reader interactively with questions and challenges, using syntactic tree diagrams throughout.
The emphasis is on understanding syntactic concepts with English as the focal language, rather than developing advanced knowledge of English grammar. Each chapter concludes with a summary of points to remember, and exercises (solutions not given in the book). There is a good bibliography for further reading, and a useful glossary. The index is good, but not aimed at going straight to detailed points. Indeed the whole book is about principles rather than fine details. It is thus best as a bridge to formal study of syntax, rather than more detailed study of English as a language.

Angela Downing and Philip Locke (2006) English Grammar. A University Course, 2nd edn, Routledge. ISBN 0 415 28787 1.
This is a 60 module university-level course in English grammar, approached largely from Halliday’s Systemic Functional Grammar (see Wikipedia), and is aimed particularly at those whose first language is not English. It thus has a very different structural basis, and terminology, which could make it difficult to use with a reference grammar, for instance. If you wish (or have) to use this approach, this is an excellent and mature text which covers most important topics, although in comparison to other approaches some areas are not as detailed, perhaps. Periodic modules in the course include excellent summaries, which use tables effectively, a list of recommendations for further reading, and exercises. Answers are also provided at the back. The index is good too.
If you have tried more conventional grammars and struggled with them, this might work better for you, but you should study the book carefully before committing to it.

Rodney Huddleston and Geoffrey K Pullum (2005) A Student’s Introduction to English Grammar, Cambridge UP. ISBN 978 0 521 61288 3.
This is the student lead-in to the authoritative Cambridge Grammar by the same pair of authors, and is an excellent companion to it. You can breeze through a briefer and more accessible account of a topic here, before going on to the full detail of their reference grammar. However it also has strong merit as a standalone student grammar, which accomplishes more in its 300 or so pages than others do in nearly double the page count. Some topics are tackled in unusual order or manner: for instance, much of morphology is left to the end, rather than prefacing syntax. Invariably this is because the approach used here is the most effective and lucid.
The approach is strongly anti-prescriptive, with occasional boxout ‘Prescriptive grammar notes’ pointing out issues which arise when reading more prescriptive grammars. Presentation is probably the clearest of all the student grammars, with intelligent use of colour, emboldening, and examples. Each chapter ends with a page or so of exercises, for which solutions are not given in the book (but are at its companion site, see below). A mature discussion, rather than simple list, of further reading is included, together with a thorough glossary. Although the single index works satisfactorily, it is perhaps the least impressive feature of this exceptional book.
Strongly recommended for anyone with an interest in English grammar, no matter which direction you approach it from.

Which student grammar should you buy?

All of them! Seriously, you may be better buying several of those listed above and only one reference grammar.

If you can only buy one, the I think it should be Huddleston and Pullum. However I recommend that if at all possible you browse at length through that and Aarts, to see which of the two approaches works best for you. If you can, get both, and consider adding Biber, Conrad and Leech, which could substitute for a reference grammar, at least temporarily. Börjars and Burridge and Downing and Locke are probably better if you have a special need for their specific strengths.

Wikipedia’s articles on different aspects of grammar, and English grammar in particular, can be very good indeed, and are usually worth checking. However it lacks the systematic approach of the texts above, and can be quite weak in parts. It is also prone to error or distortion.

If you want a short overview based on Huddleston and Pullum, then this should be ideal. There are other good introductory resources here, the support site for their student grammar above.