By 1960, de Havilland had been acquired by the Hawker Siddeley group.
After the de Havilland takeover, Airco was disbanded.
Hunting was marshalled into the competing newly formed British Aircraft Corporation (BAC); their departure removed any putative possibility of the Hunting 107 (later the BAC One-Eleven) being marketed alongside the D.H.121 as a complementary, smaller member of the same airliner family.
Fairey Aviation, partially incorporated into Westland Aircraft, also left the D.H.121 project.
With the move to Hawker Siddeley Aviation, the designation was eventually revised to the HS 121.
The reorganisation of the industry had compounded upon the delays caused by BEA's changes to the specification, which had in turn harmed the Trident's competitiveness against the Boeing 727.

The rival Boeing 727 had quickly established a lead over the Trident.
The 727's early lead only strengthened it in subsequent competitions; one such example is Trans Australia Airlines, which had determined the Trident to be superior to the Boeing 727 from an operational standpoint, however it was also viewed as having been commercially risky to choose a different fleet from rival airlines such as Ansett Australia, who had already selected the 727.
By 1975, only 117 Tridents had been sold against over 1,000 727s.

According to Woods, a significant opportunity that may have enabled the Trident to catch up with the 727 was lost during the 1960s in the form of two competitions for a maritime patrol aircraft; a NATO design competition to replace the Lockheed P-2 Neptune, and Air Staff Requirement 381, which sought a replacement for the Royal Air Force's piston-engined Avro Shackleton.
Amongst the various submissions that had been produced in response was a bid by Avro, part of the Hawker Siddeley Group, which was designated as the Avro 776.
The proposed Avro 776 mated the Trident's fuselage with a redesigned and enlarged wing along with more powerful Rolls-Royce RB178 engines capable of 16,300 lb of thrust.
In addition to the maritime patrol requirement, Avro envisioned that the aircraft could be utilised in various military roles, including as a 103-seat troop transport as well as being armed with up to four Skybolt air-launched ballistic missile (ALBM) as a nuclear-armed bomber.
In addition to Avro's proposals, Armstrong Whitworth had also proposed their own military variants of the Trident.

Later revisions of the Avro 776 substituted the RB.178 engine for the newer Rolls-Royce RB211 turbofan engine, the development of the latter being supported by the 776's procurement if selected.
Rolls-Royce Limited, having shelved development of the Medway following the Trident's redesign, was keen to develop an engine to slot between the 10,000 lb Spey engine and the 20,000 lb Rolls-Royce Conway engine; if such an engine had been produced, it could have equipped new versions of the civil Trident as well.
Furnished with a more capable engine that could provide more thrust than the Spey was capable of, an extended fuselage could also have been adopted and existing landing restrictions could have been discarded; overall, the Trident would have been a far closer match to the 727.
Wood summarised the importance of this prospective development as: "For the Trident programme, the RB.177 would have been a God-send".

At one point, the Avro 776 looked set to win the competition to be selected as the RAF's new maritime patrol aircraft.
However, due to a desire to cut costs, the RAF decided to issue an entirely new Operational Requirement, under which the demands for speed, endurance, and capacity had all been diminished.
As a result of the changed requirement, the design team was recalled and the Avro 776 was entirely sidelined for a new proposal.
This new proposal, based upon the de Havilland Comet's fuselage, had little to do with the Trident save for the use of its existing Spey engines; this would go on to be selected and procured as the Hawker Siddeley Nimrod.
As a result of this loss, prospects for an enlarged, higher-power Trident effectively evaporated.
By 1960, de Havilland had been acquired by the Hawker Siddeley group. After the de Havilland takeover, Airco was disbanded. Hunting was marshalled into the competing newly formed British Aircraft Corporation (BAC); their departure removed any putative possibility of the Hunting 107 (later the BAC One-Eleven) being marketed alongside the D.H.121 as a complementary, smaller member of the same airliner family. Fairey Aviation, partially incorporated into Westland Aircraft, also left the D.H.121 project. With the move to Hawker Siddeley Aviation, the designation was eventually revised to the HS 121. The reorganisation of the industry had compounded upon the delays caused by BEA's changes to the specification, which had in turn harmed the Trident's competitiveness against the Boeing 727.
The rival Boeing 727 had quickly established a lead over the Trident. The 727's early lead only strengthened it in subsequent competitions; one such example is Trans Australia Airlines, which had determined the Trident to be superior to the Boeing 727 from an operational standpoint, however it was also viewed as having been commercially risky to choose a different fleet from rival airlines such as Ansett Australia, who had already selected the 727. By 1975, only 117 Tridents had been sold against over 1,000 727s.
According to Woods, a significant opportunity that may have enabled the Trident to catch up with the 727 was lost during the 1960s in the form of two competitions for a maritime patrol aircraft; a NATO design competition to replace the Lockheed P-2 Neptune, and Air Staff Requirement 381, which sought a replacement for the Royal Air Force's piston-engined Avro Shackleton. Amongst the various submissions that had been produced in response was a bid by Avro, part of the Hawker Siddeley Group, which was designated as the Avro 776. The proposed Avro 776 mated the Trident's fuselage with a redesigned and enlarged wing along with more powerful Rolls-Royce RB178 engines capable of 16,300 lb of thrust. In addition to the maritime patrol requirement, Avro envisioned that the aircraft could be utilised in various military roles, including as a 103-seat troop transport as well as being armed with up to four Skybolt air-launched ballistic missile (ALBM) as a nuclear-armed bomber. In addition to Avro's proposals, Armstrong Whitworth had also proposed their own military variants of the Trident.
Later revisions of the Avro 776 substituted the RB.178 engine for the newer Rolls-Royce RB211 turbofan engine, the development of the latter being supported by the 776's procurement if selected. Rolls-Royce Limited, having shelved development of the Medway following the Trident's redesign, was keen to develop an engine to slot between the 10,000 lb Spey engine and the 20,000 lb Rolls-Royce Conway engine; if such an engine had been produced, it could have equipped new versions of the civil Trident as well. Furnished with a more capable engine that could provide more thrust than the Spey was capable of, an extended fuselage could also have been adopted and existing landing restrictions could have been discarded; overall, the Trident would have been a far closer match to the 727. Wood summarised the importance of this prospective development as: "For the Trident programme, the RB.177 would have been a God-send".
At one point, the Avro 776 looked set to win the competition to be selected as the RAF's new maritime patrol aircraft. However, due to a desire to cut costs, the RAF decided to issue an entirely new Operational Requirement, under which the demands for speed, endurance, and capacity had all been diminished. As a result of the changed requirement, the design team was recalled and the Avro 776 was entirely sidelined for a new proposal. This new proposal, based upon the de Havilland Comet's fuselage, had little to do with the Trident save for the use of its existing Spey engines; this would go on to be selected and procured as the Hawker Siddeley Nimrod. As a result of this loss, prospects for an enlarged, higher-power Trident effectively evaporated.
Hawker Siddeley Trident