Sir Alex Younger has warned that while witnessing Bashar al-Assad’s retreat may be ‘satisfying’, a breakdown in order poses a threat to the UK.

“It is hard not to derive satisfaction from any setback Bashar experiences”, Sir Alex told the BBC Today programme, adding: “I certainly would never go so far as to claim that Bashar’s rule forms any form of long term stability.

“So no, I don’t want him back in charge of Aleppo but equally you cannot pretend that a hard line Islamist group, albeit one trying to moderate its image, presents a good future either.

“It seems to me more likely that we are seeing a reignition of the civil war in all its dimensions.”

Sir Alex, who served as chief of MI6 from 2014 to 2020, added that the Syrian Democratic Forces were holding many Isis prisoners and their families.

“The camps represent a hot bed of radicalisation and haven’t been sorted out - if the SDF were to go off the job our security situation here would worsen.”