"I'm so proud watching you thrive into the young man you have become!” Anstead wrote on Instagram Sunday
The Celebrity IOU: Joyride host, 44, celebrated his teenager’s birthday on Sunday with a touching tribute and collection of throwback photos of father and son.
“This is a huge year of A levels and finally time to drive!!!" he continued, including a snap of a younger Archie sitting in the driver's seat of an old car.
“I love you me dooood! You inspire me every day! It’s crazy to think where did those 17 years go? In a blink! One lucky daddo! ❤️❤️🥰 x," Anstead concluded his caption.
The British car expert shares son Archie, as well as daughter Amelie, 19, with ex-wife Louise Storey. He is also dad to son Hudson, 3, whom he shares with his second ex-wife, HGTV star Christina Hall.
Anstead is now in a relationship with Renée Zellweger, whom he began dating shortly after meeting her on the set of his Discovery+ show in early June 2021.
Last month, he shared the first photo of his actress girlfriend, 54, smiling with his two older children ahead of their attendance at a formal event.
In the picture, Anstead has an arm around the Oscar winner, who is in between her beau and Archie. Amelie stands on the opposite side of her brother in the picture.
"@fosgoodwood How it started, How it ended 😂 x @landrover @radfordmotors," he captioned the group shot.
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An entertainment source told PEOPLE in March, "Ant is very happy with Renée. He really loves her.” The insider added that Anstead could be leaning towards proposing soon, but "Ant doesn't want to rush things."
Despite maintaining busy schedules, both Anstead and Zellweger "very much prioritize Hudson," the source told PEOPLE. "They want him to be happy and comfortable."
A month later, a separate source revealed to PEOPLE that the couple "found a house that they both love and are moving in together.” While Anstead didn't disclose the location of the property, he previously told PEOPLE, "I'm going to absolutely keep a base in and around Laguna."
The insider added of the couple, "They are very happy and in love. They have tried to keep their relationship private and low-key because of Hudson.”
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