Last season’s F2 runner-up replaced Antonio Giovinazzi for the opening practice session of the weekend.

Ilott was set to make his F1 debut in the Eifel Grand Prix for Haas but due to FP1 at the Nurburgring being called off due to poor weather, Ilott never got his chance.

The British driver ended the session 17th fastest overall, 0.4s shy of Kimi Raikkonen.

Reflecting on his first official F1 outing at Portimao, Ilott said: “Obviously for me I was still taking it easy as well. It was interesting to experience it. But once I was up to speed with the tyres and getting used to it, I think I finished the run on the hards, one-tenth off Kimi, which is not too bad at the time.

“Then we went to the softs and I completely got caught out at the beginning by how much grip and also getting the tyres in. So struggled a bit then but then we came in, rebalanced and then I think with the tyre mileage I had, I didn’t do a bad time.

“Overall, building consistently, was very happy with the session, got through all the run plan that we needed to and discovered the limitations we have as a team and as a driver as well. Lots learned from my side and lots learned from the team. So yeah, big thanks to Alfa Romeo for giving me the opportunity.”

Ilott is a member of Ferrari's driver academy and he's enjoyed a series of tests in its 2018 challenger at the team's circuit in Fiorano. 

The 22-year-old commented how “unbelievable” modern F1 machinery performs on low fuel. 

“I’ve had a few opportunities now, a few highs and lows as well,” Ilott added. “From that side, to get the first experience of a session was a wow factor, but these machines over one lap are incredible. It’s unbelievable how fast they are, but I think it was quite nice for me after the session to step back and enjoy the moment afterwards.

“In the moment, you’re focused on what you’re doing. It’s not that the wow factor is gone, when I take a step back it’s there. It’s just when you’re in the moment, you have to make the most out of it.”