1955 AD., United Kingdom, Elizabeth II, Royal Mint, 3 Pence, KM 900.

United Kingdom of Great Britain & Northern Ireland, Elizabeth II, engravers: Mary Gillick (obverse) and William Maving Gardner (reverse), standard circulation issue, Royal Mint, Tower Hill Site, London, 1955 AD.,
3 Pence (21-22 mm / 6,70 g), nickel-brass (70% copper, 24.5% zinc, 5.5% nickel), dodecagonal (12-sided) shape, 6,80 g theor. mint weight, mintage 41.075.200 , axis medal alignment ↑↑ (0°), plain edge,
Obv.: + ELIZABETH·II·DEI·GRATIA·REGINA·F:D: , (Elizabeth II Dei Gratia Regina Fidei Defensatrix - “Elizabeth the Second by the Grace of God Queen Defender of the Faith“), her laureate bust facing right, 1st portrait; without 'BRITT:OMN' in legend.
Rev.: THREE – 1955 - PENCE / W - G , a Tudor portcullis plus side chains, crown above, value flanking, date below; engraver´s initials below portcullis (below pins).
KM 900 ; Sp. 4153 .

Year / Mintage
1954 41,720,000
1954 ? proof issue
1955 41.075.200
1955 ? Proof
1956 36,801,600
1956 Proof
1957 24,294,400
1957 Proof
1958 20,504,000
1958 Proof
1959 28,499,200
1959 Proof
1960 83,078,400
1960 Proof
1961 41,102,400
1961 Proof
1962 51,545,600
1962 Proof
1963 35,280,000
1963 Proof
1964 44,867,200
1964 Proof
1965 27,160,000
1965 Proof
1966 53,760,000
1966 Proof
1967 151,780,800
1967 Proof
1970 750,476 Proof

A portcullis (from the French "porte coulissante" or gliding door) is a latticed grille made of wood, metal or a combination of the two. Portcullises fortified the entrances to many medieval castles, acting as a last line of defence during time of attack or siege. Each portcullis was mounted in vertical grooves in castle walls and could be raised or lowered quickly by means of chains or ropes attached to an internal winch.

The portcullis was the heraldic badge of the House of Beaufort, and the first Tudor king, Henry VII, who was of matrilineal Beaufort descent, adapted both the portcullis and the Tudor rose as the Tudor badge. Since then, the portcullis has been a moderately common motif of English heraldry, especially that heraldry dating from the Tudor period. The heraldic office of Portcullis Pursuivant of Arms in Ordinary, a junior officer of arms in the College of Arms at London, dates from this period.

Although the Palace of Westminster served as the official royal residence for both Henry VII and Henry VIII until 1530, the current use of the portcullis as a symbol of the Palace and of Parliament does not date from that time. Rather, the symbol was developed as part of Sir Charles Barry's plans for the rebuilt Palace after the original burned down on 16 October 1834; he conceptualized the new Palace as a "legislative castle", and the symbol of a castle gate—i.e. a portcullis—fitted well with the scheme.

Since then, the portcullis has become the primary symbol of Parliament; an office building for Members of Parliament, opened in 2001, is named "Portcullis House". During the 20th century, use of the portcullis as a symbol of Parliament spread beyond Britain and to the other Commonwealth realms; for instance, the coat of arms of Canberra features a portcullis in its crest, consciously preserving a connection between the British Parliament at Westminster and the Australian Parliament to which Canberra is home.

A portcullis was previously found on the British one penny coin; this has since been replaced by a section of the Royal Arms of the United Kingdom. The badge of the now-defunct HM Customs and Excise also bore a portcullis, symbolising the agency's role as "gatekeeper" of goods into the UK, as well as the badge of the Canada's now-defunct Customs and Excise.