Red Ensign of the United Kingdom

Quick answer

The United Kingdom’s undefaced Red Ensign has a red field with the Union Flag in the upper corner next to the flagpole. It is the ordinary ensign for British merchant and civilian shipping. Royal Navy regulations distinguish this plain version from authorised versions carrying a badge or seal. See The King’s Regulations, paragraph 9154.

Its customary hoist:fly proportion is 1:2, meaning twice as long as it is high. This is a manufacturing convention identified by the Flag Institute, rather than a dimensional rule established by the legislation cited here.

Specification and evidence limits
Feature	Description	Evidence status
Design	Red field with the Union Flag in the upper hoist canton; no additional badge in the undefaced version.	Identification of the plain Red Ensign; authorised defaced versions are separate variants.
Proportions	1:2 hoist:fly.	Customary maritime proportions according to the Flag Institute, not a statutory measurement asserted by this record.
Legal identity	The undefaced Red Ensign is the flag British ships are generally entitled to fly, subject to the exceptions in section 2.	Merchant Shipping Act 1995, section 2.
Colours	Red field; red, white and blue within the Union canton.	No ensign-specific physical colour standard has been verified for this record. No HEX, RGB, CMYK or Pantone values are asserted as mandatory.
Detailed geometry	Canton dimensions, cross widths and production tolerances are not specified numerically here.	No authoritative Red Ensign construction sheet was verified; measurements must not be inferred from an illustration.

Construction and reproduction notes

Use the customary 1:2 outline as a reference proportion, while retaining the distinction between common manufacture and an official production specification. The Union canton has an asymmetric arrangement of diagonal white borders: the broader white diagonal is uppermost at the hoist. The Flag Institute’s Union Flag specification explains this orientation and provides a recommended Union construction; it is not an ensign-specific manufacturing standard.

Screen colours are approximations and do not certify textile colours. An editorial reconstruction should be identified as such, with its geometry and colour sources stated.

For the canton’s constituent flag, see the Flag of the United Kingdom.

Current use and variants

Section 2 of the Merchant Shipping Act 1995 establishes entitlement to the undefaced Red Ensign, subject to specified exceptions. The rule should not be read as saying that every British vessel must display an identical ensign in every circumstance.

The Maritime and Coastguard Agency’s Red Ensign Group overview explains that the group includes the United Kingdom, Crown Dependencies and participating Overseas Territories. Ships on these registers are British ships and may fly the Red Ensign or an appropriate authorised defaced version. This record concerns the plain United Kingdom ensign.

Historical context

The Red Ensign also has a naval history. Royal Museums Greenwich catalogues a surviving naval example as Red Ensign (before 1864), object AAA0775, dated 1801–64. That is the museum’s date range for an individual object, not an exact adoption date for the design.

Royal Navy regulations, paragraph 9154, explain that after the squadronal system ended in 1864, the Red Ensign was reserved for merchant and civilian shipping not authorised to wear other national colours. This marks a change in allocation, not the first appearance of a red ensign.

Historical objects also demonstrate why surviving cloth should not be treated as a precise construction standard. Greenwich’s merchant ensign AAA0342 is dated only after 1801 and measures 914.4 × 1803.4 mm. Those are recorded object dimensions, not a prescribed ratio or manufacturing tolerance.