[6][7] He had become frustrated by the facilities available at the British Museum Library, where he was often unable to find a seat (obliging him to perch on ladders), where he complained that the enforced close confinement with his fellow readers gave him a "museum headache", where the books were unavailable for loan, and where he found the library's collections of pamphlets and other material relating to the French Revolution and English Civil Wars inadequately catalogued.

[8] Carlyle's eventual solution, with the support of a number of influential friends, was to call for the establishment of a private subscription library from which books could be borrowed.

(Sir) Charles Hagberg Wright, who served as Secretary and Librarian from 1893 to 1940, is remembered as "the real architect of the London Library as it is today".

[9] He oversaw the rebuilding of its premises in the 1890s, the re-cataloguing and rearrangement of its collections under its own unique classification system, and the publication of its catalogue in 1903, with a second edition in 1913–14 and later supplements.

In 1957 the Library received an unanticipated demand from Westminster City Council for business rates (despite being registered as a tax-free charity), and the Inland Revenue also became involved.

[11] Financial donations reached £17,000, and an auction of books, manuscripts and artworks on 22 June 1960 raised over £25,000 – enough to clear debts and legal expenses of £20,000.

The identification of several rare books put up for auction as having been stolen from the Library led the police to investigate Jacques and to his eventual prosecution and conviction.

[14] The Library's collections, which range from the 16th century to the present day, are strong within the fields of literature, fiction, fine and applied art, architecture, history, biography, philosophy, religion, topography, and travel.

Colin Wilson remembered his first visit to the library in the mid 1960s: "I have always had an obsession about books, and in this place I felt like a sex maniac in the middle of a harem".

[20]Peter Parker wrote in 2008: One of the pleasures and privileges of belonging to the London Library is wandering through its labyrinthine book-stacks with no particular aim in mind.

... One of the best places to do this is in the capacious Science and Miscellaneous section, that glorious omnium gatherum subdivided into such widely divergent subjects as Conjuring and Colour-Blindness, Domestic Servants and Duelling, Gas and Geodesy, Human Sacrifice and Hypnotism, Laughter and Lotteries, Pain and Poultry, Sewage Disposal and Somnambulism, or Vinegar and Vivisection.

[21] And Roger Kneebone wrote in 2015: Because the Library's classification – especially in Science and Miscellaneous – is so idiosyncratic, it doesn't conform to the systems that populate my own mind.

With those exceptions, it was formerly library policy to retain virtually all items acquired since its foundation, on the grounds that, as books are never entirely superseded, and therefore never redundant, the collections should not be weeded of material merely because it was old, idiosyncratic or unfashionable.

[29][30][31] In 1896–1898 the premises were completely rebuilt to the designs of James Osborne Smith, and this building survives as the front part of the present library complex.

The facade, overlooking St James's Square, is constructed in Portland stone in a broadly Jacobethan style, described by the Survey of London as "curiously eclectic".

A mezzanine was inserted within the Art Room in the early 1970s; four floors of bookstack were constructed above the north bay of the reading room in 1992; and in 1995 the Anstruther Wing (named after its benefactor, Ian Anstruther) was erected at the extreme rear of the site, a nine-storey building on a small footprint designed principally to house rare books storage.

[38] In 2004, the Library acquired Duchess House, a four-storey 1970s office building adjoining the north side of the existing site, which increased overall capacity by 30%.

The architects for the redevelopment were Haworth Tompkins with Price & Myers acting as consulting structural engineers; while the toilets were designed in collaboration with Turner Prize-winning artist Martin Creed.

[45] In 2011 the Library launched its Student Prize, a writing competition open to final-year undergraduates at higher education institutions in the UK.

The theme was "The future of Britain lies with the right-hand side of the brain", and the winner was announced in March 2012 as Ben Mason, a student at Trinity College, Oxford.