engineering

No. 1 Croydon

No. 1 Croydon is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand No. 1 Croydon rather than just read about it. In short: No. 1 Croydon (formerly the NLA Tower, and colloquially the 50p Building, the Weddingcake or the Threepenny bit building) is a tall building at 12–16 Addiscombe Road, Croydon, Greater London, next to East Croydon station. It was designed by Richard Seifert & Partners and completed in 1970.

Key takeaways

No. 1 Croydon belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect No. 1 Croydon to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of No. 1 Croydon from memory before moving on to harder problems.

Reference excerpt

No. 1 Croydon (formerly the NLA Tower, and colloquially the 50p Building, the Weddingcake or the Threepenny bit building) is a tall building at 12–16 Addiscombe Road, Croydon, Greater London, next to East Croydon station. It was designed by Richard Seifert & Partners and completed in 1970. It has 24 storeys and is 269 feet (82 m) high. NLA stood for Noble Lowndes Annuities, the original principal tenant (subsequently taken over by the Hill Samuel Group). It was one of many new buildings constructed in the growing town of Croydon in the 1960s. The development of tall buildings was later encouraged in the 2004 London Plan, which led to the erection of new skyscrapers as Greater London went through a high-rise boom.

Construction The building was erected between 1968 and 1970. Its distinctive appearance arises from its octagonal floor plans (not, in fact, regular octagons, but squares with splayed or truncated corners), set above one another on alternating orientations. Construction was delayed by the objections of Miss Kathleen Harding, a solicitor and leasehold tenant of the Victorian East Bridge House, which stood on part of the intended site. She refused to leave, and the new tower had to be erected with East Bridge House still standing. The house was eventually demolished in 1973.

Restoration project A refurbishment programme costing over £3.5 million was completed in early 2007. It included a six-month exterior cleaning project, a new lobby, landscaping and common areas, and refurbishment of the top ten floors to provide 74,543 square feet (6,925 m2) of high spec, air-conditioned office accommodation. A substantial amount of work had already been done to improve the façade of the tower. It was identified in a Channel 4 programme as one of the UK's top eyesores. A spokesman for building restoration firm Triton said: "Work is running to schedule and within budget."

Occupiers No. 1 Croydon is occupied by a number of companies and organisations, including Atkins, Directline holidays and dotdigital.

In 2014, a branch of Sainsbury's Local was opened in part of the former courtyard on the north side of the building, effectively forming a part of the structure. The new building attracted criticism on aesthetic grounds and also in respect of safety due to its proximity to the Tramlink track bed.

Other names No. 1 Croydon was originally known colloquially as the Threepenny Bit Building, due to its resemblance to a number of threepence coins stacked on top of each other. After the coins stopped being used following decimalisation the building eventually gained the alternative nickname the 50p Building, as it also resembles a stack of the now more familiar 50p pieces; and it is also referred to as The Wedding Cake. The resemblance to threepenny and 50p coins is approximate, as the building's floors are octagonal (8 sides) whereas threepenny coins were dodecagonal (12 sides) and 50p coins are heptagonal (7 sides).

In popular culture The building was used as part of an establishing shot in Croydon in the opening credits of the 1980s British sitcom Terry and June. It also appeared in the Black Mirror interactive film Bandersnatch, as housing the offices of fictional game software developer Tuckersoft.

Applications for listing The campaign for heritage listing No. 1 Croydon is supported by the Twentieth Century Society, but this was turned down by English Heritage in 2013. Following the announcement of a proposal to convert the building into flats, a second application for listing was made in August 2024, but this was also rejected in March 2025.

Illustrations

Worked examples

Example 1 — a first encounter with No. 1 Croydon

Start with the simplest possible case. Write down what No. 1 Croydon claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to No. 1 Croydon before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about No. 1 Croydon ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of No. 1 Croydon

In research: No. 1 Croydon appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses No. 1 Croydon in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: No. 1 Croydon is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1970 establishments in England, Buildings and structures completed in 1970, Croydon 2020, so understanding it makes those chapters shorter.
In everyday life: Look for No. 1 Croydon outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study No. 1 Croydon in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what No. 1 Croydon means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain No. 1 Croydon out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is No. 1 Croydon in simple terms?

Why does No. 1 Croydon matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study No. 1 Croydon?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on No. 1 Croydon.