Two RAF tornados spent seven hours in the skies over ISIL positions in Iraq on Saturday, less than a day after British MPs voted to send UK fighter jets to the war-torn country.
But the aircraft returned to their airbase in Cyprus without carrying out any air strikes on the militant group.
The UK military said the intelligence gathered by the jets’ “highly sophisticated surveillance equipment will be invaluable”.
The British aircraft are loaded with laser-guided bombs and missiles.
Friday’s parliamentary vote authorised the use of jets but not British troops. It also restricted any UK operations to Iraq rather than Syria.
The US has conducted air strikes over Iraq since early August and over Syria since Tuesday.
As well as Britain, the coalition against the militant group ISIL is supported by several Gulf and European nations.