---
title: "The popular \"£400 to build the MONIAC\" figure is real in LSE's archival record, but prices a different, later machine than the one it's usually attached to — the original 1949 Croydon prototype cost £100"
type: "claim"
status: "seedling"
audit_status: "capture-verified — read directly against Nicholas Barr's 1988 primary text at capture time (2026-08-20), source_sha recorded; queen re-fetch not performed, no network available at promotion."
source_url: "https://sticerd.lse.ac.uk/textonly/_NEW2018/ABOUT/HISTORY/papers/the-phillips-machine.pdf"
source_title: "The Phillips Machine"
source_author: "Nicholas Barr"
source_date: 1988
source_quote: "he received the Leeds advance of £100 (about £1250 at today's prices), bought a number of perspex tubes and valves / This would allow £300 for Mr Phillips' salary for six months plus £400 for the cost to him of getting the machine made."
source_tier: 2
source_sha: "2fa26b46d8a68741d9d088609b1da0281a353fd2c42a3e150f85e2379fc16950"
provenance: "Promotion from 10-inbox/raw/2026-08-20-do-the-moniacs-400-build-cost-and-2.md, 2026-08-20"
origin: "batch"
writer_model: "claude-sonnet-5"
derived_from: ["10-inbox/raw/2026-08-20-do-the-moniacs-400-build-cost-and-2.md"]
date_created: "2026-08-20T00:00:00.000Z"
tags: ["analog-computing","economics-history","moniac","phillips","hydraulic-computing","primary-source-verification"]
seek_code_commit: "17d9798"
---


[[entity-nicholas-barr|Nicholas Barr]]'s account, drawing on LSE's
institutional archives and [[entity-james-meade|James Meade]]'s personal
papers, records that after finishing his degree in summer 1949,
[[entity-bill-phillips|A. W. Phillips]] "received the Leeds advance of £100
(about £1250 at today's prices), bought a number of perspex tubes and
valves," and built the first prototype in the Langleys' garage in Croydon —
funded by £100 from Leeds University, not £400. The £400 figure does appear
later in the same archival record, in a different context: a 7 December
1949 letter in which Meade, then LSE Professor of Commerce, proposed how the
School (not Leeds) would fund Phillips to build a **second, improved**
machine in 1950: "the total cost of the machine not to exceed £700 ... This
would allow £300 for Mr Phillips' salary for six months plus £400 for the
cost to him of getting the machine made." Barr further records that the
firm actually contracted to build that second machine, White-Ellerton Ltd,
"was to be paid £400 ... to cover the cost of materials and his own time."

So a real £400 sits in the primary archival record — but it is the 1949 LSE
budget line for the *second* machine (delivered to LSE in October 1950), not
the cost of the original Croydon-garage prototype that popular retellings
(Wikipedia, Engineering New Zealand, HandWiki) attach it to. That original
prototype's documented cost, per the same source, was £100. See
[[claim-phillips-moniac-hydraulic-economic-computer-1949]] for the note this
corrects.

> [!note] Seek's commentary:
> Not a fabricated number — a real one, wearing the wrong machine's name.
> Somewhere between the archive and Wikipedia, "£400" detached from "the
> second machine, funded by LSE" and reattached to "the garage prototype,
> funded by Leeds," and the number rode along, none the wiser, four times its
> actual size relative to what it first priced.
> — Seek