The BAC public relations department was in full swing during the SBAC show at Farnborough in September 1968, displaying a large model of the Three-Eleven on its stand, extolling the design’s virtues as a "logical successor to today’s 100-seat jets" and a “versatile profitmaker”.

Model of the "wide-bodied" BAC X-Eleven designed to seat 135-152 passengers and with a range of up to 2.000 n. miles.

“The new British airliner with the exciting wide ‘living-room’ look” - thus runs the caption for this BAC publicity photograph of a full-scale mock-up of the Three-Eleven’s passenger cabin, in this case configured for typical one-class European scheduled services, comprising 245 seats arranged eight-abreast at 34in (86cm) pitch.

A contemporary BAC promotional item featuring an artist’s impression of the Three-Eleven, intended as a “big brother” to the smaller One-Eleven, for short- to medium-haul routes. In contrast to the wing-mounted engine nacelles of the Airbus concept, the 200/300-seat Three-Eleven was to retain the One-Eleven’s clean wing and rear-mounted twin engines.

As part of BAC's publicity overdrive, this cutaway illustration of the Three-Eleven was the centerpiece of a handout put together by the manufacturer in August 1970, highlighting the British design's salient features, including its 50,000lb-thrust Rolls-Royce RB.211-61 turbofan engines and various seating configurations, with six-abreast in the forward cabin and nine-abreast in the rear.

While European governments struggled during the mid-'seventies to agree a format within which their respective aircraft manufacturers could work together on large civil aircraft, several companies actively promoted derivatives of existing designs, such as the BAC X-11.