University College London (UCL) was founded on 11 February 1826, under the name London University, as a secular alternative to the strictly religious universities of Oxford and Cambridge. It was founded with the intention from the beginning of it being a university, not a college or institute. However its founders encountered strong opposition from the Church of England, the existing universities and the medical schools which prevented them from securing the Royal Charter under the title of "university" that would grant "London University" official recognition and allow it to award degrees. Thus it was not until 1836, when the latter-day University of London was established, that it was legally recognised (as a college, under the name of University College, London) and granted the authority to submit students for the degree examinations of the University of London.
In 1900 when the University of London was reconstituted as a federal university, UCL became one of the founding colleges. Through much of the 20th century it surrendered its legal independence to become fully owned by the University of London. It was rechartered as an independent college in 1977, has received government funding directly since 1993, and gained the power to award degrees in its own right in 2005. From 2005, the Institute has branded itself as UCL (rather than University College London) and has used the strapline "London's Global University".
UCL's foundation date of 1826 makes it the third oldest university institution in England, and it was certainly founded with the intention of it being England's third university, but whether or not UCL is actually the third oldest university in England is questionable: UCL makes this claim on its website, but so do the Universities of London (1836) and Durham (1832). Other higher education institutions in England have institutional ancestry preceding their formation as "universities": for example what is now the University of Nottingham can trace some elements back to 1798 but only began university-level teaching with the foundation of the first civic college in 1881 (royal charter as University College Nottingham in 1903), and did not gain University status (via a new royal charter) until 1948. Conversely, King's College London (KCL) was founded after UCL, but received its Royal Charter (granting it legal existence as a corporation) in 1829, before UCL, so arguably is older, leading King's College students to claim the title of third oldest university in England for their institute.