These are on the fleet list today for the UK:
2015 EMBRAER LEGACY 500 55000025 G-MRFX
2015 EMBRAER LEGACY 500 55000027 G-FXFX
2006 EMBRAER LEGACY 600 14500952 G-ERFX
2020 EMBRAER PRAETOR 600 55020121 G-FHFX
2020 EMBRAER PRAETOR 600 55020122 G-FLFX
2021 EMBRAER PRAETOR 600 55020142 G-FTFX
2015 LEARJET 75 45-501 G-RSFX
2001 NEXTANT 400XTi RK-317 G-FXRS
However Flexjet also own Sirio in Italy (
www.sirio.aero) who operate/manage (but may not own):
1997 BEECHJET 400A RK-148 I-TOPF
2019 CHALLENGER 350 20805 I-FORZ
2004 FALCON 2000 191 I-GEFD
2010 FALCON 2000LX 2000LX-191 I-PBRB
2009 FALCON 2000LX 2000LX-204 I-FEDN
2010 FALCON 2000LX 2000LX-213 I-MOFI
2004 FALCON 50EX 50-339 I-PBRA
2010 FALCON 7X 7X-81 I-JAMI
2020 GLOBAL 5500 60027 I-DBRR
2005 GULFSTREAM G550 5071 I-LUXO
2011 GULFSTREAM G550 5314 I-ADVD
2015 GULFSTREAM G550 5518 I-DELO