Unlike the US system, the proper name is the principal part of an
aircraft's formal designation in British service.  The full designation
consists of the name, a letter or set of letters indicating the role, and a
mark number; in a few cases the mark number is followed by a letter
indicating a modification.  The full designation is written as, for
example, "Tornado GR.1A", or sometimes "Tornado GR Mk 1A" (the Tornado GR.1
is the ground attack/reconnaissance version of the Tornado; the GR.1A is a
variant in which one of the two guns is replaced by reconnaissance gear).

For export versions, the role letters are usually left out, and the mark
numbers are restarted from a high number, usually 50 (for example, the
Indian Navy's Sea Harriers are Mk 51).

Before WW2, mark numbers alone were used, and were written in Roman
numerals; during the war, the role letters were added, and conventional
numerals were used for mark numbers above 20.  The Roman numerals were
dropped altogether after the war; apart from that, the system has remained
largely unchanged.

Role letters (an asterisk indicates an obsolete code):

    AEW   = Airborne early warning
    AH    = Army helicopter
    AL    = Army liaison
    AS    = Anti-submarine (*)
    B     = Bomber
    B(I)  = Bomber/interdictor
    B(K)  = Bomber/tanker
    B(PR) = Bomber/photo-reconnaissance
    C     = Cargo transport
    CC    = Communications (also used for VIP transports)
    E     = Electronic warfare
    F     = Fighter
    FA    = Fighter/attack
    FAW   = All-weather fighter (*)
    FB    = Fighter/bomber (*)
    FG    = Fighter/ground attack
    FGA   = Fighter/ground attack
    FGR   = Fighter/ground attack/reconnaissance
    FR    = Fighter/reconnaissance
    FRS   = Fighter/reconnaissance/strike
    GA    = Ground attack
    GR    = Ground attack/reconnaissance
    HAR   = Search and rescue helicopter
    HAS   = Anti-submarine helicopter
    HC    = Cargo helicopter
    HCC   = Communications helicopter (also used for VIP transports)
    HT    = Training helicopter
    HU    = Utility helicopter
    K     = Tanker
    KC    = Tanker/transport
    Met   = Weather reconnaissance (*)
    MR    = Maritime reconnaissance
    NF    = Night fighter (*)
    PR    = Photographic reconnaissance
    R     = Reconnaissance
    S     = Strike
    SR    = Strategic reconnaissance
    T     = Trainer
    TF    = Torpedo fighter (*)
    TT    = Target tug
    U     = Unmanned drone
    W     = Weather reconnaissance