While based on the Bombardier Global Express ultra long-range business jet, the prime contractor for the Sentinel was the American defence firm Raytheon, which supplied most of the mission systems and performed the integration work.

In 2010, the British government's Strategic Defence and Security Review (SDSR) announced its intention to "withdraw the Sentinel airborne ground surveillance aircraft once it is no longer required to support operations in Afghanistan.

"[4] The 2010 decision was reversed in 2014 by Prime Minister David Cameron and in the 2015 SDSR, the British government announced that the type's retirement would be delayed and that it would remain in service "into the next decade".

The cockpit featured a centrally positioned pull-down screen capable of displaying a moving map, along with Link 16 datalink information and defensive aids subsystem (DASS) data.

The DASS comprised a towed radar decoy, missile approach warning system, and chaff and flare dispensers which could be operated in automatic, semi-automatic or manual mode.

[7] Raytheon claimed that the radar could be modified to match the maritime surveillance capability of the cancelled Nimrod MRA4, and the ground stations could be adapted to receive data from different types of unmanned aerial vehicles (UAVs), including the Watchkeeper, MQ-9 Reaper and the future Scavenger programme.

[16] In addition to its presence in the Afghan theatre, the Sentinel routinely performed surveillance flights over the Baltic Sea, monitoring military forces stationed in the Kaliningrad Oblast and Belarus; during such missions the type was frequently intercepted by Russian Sukhoi Su-27s.

[7] In 2010, the UK government's Strategic Defence and Security Review announced its intention to "withdraw the Sentinel airborne ground surveillance aircraft once it is no longer required to support operations in Afghanistan.

[21] On 18 May 2014, the MoD announced that a Sentinel had departed to Ghana as part of Operation Turus to assist in the search for the 223 schoolgirls abducted by the Islamic militant group Boko Haram in Nigeria on 14 April 2014.

[13] In the absence of UK government backing, Raytheon self-financed development work for over five years on a mid-life upgrade of the Sentinel's mission systems, referred to as Overseer, but this was not applied.

[7] On 26 March 2015, the MOD announced the deployment of two Sentinel aircraft in support of Operation Shader to provide surveillance to coalition forces fighting as part of the Military intervention against ISIL.

[27][28][29] Despite the RAF reportedly hoping to retain the entire five-strong fleet,[26] it was announced, while the type's service date would be extended into 2021, that the number of operational Sentinels would be cut to four aircraft with effect from 1 April 2017.