The Essex quartet were among the guests who joined PG Tips and its iconic Monkey on a special cruise down the river on Monday morning (16 May).
But this was no normal Monkey... this was a massive six-metre high statue of Monkey created from 110,486 fabricated green tea leaves!
It was all to raise awareness for a new PG Tips Green Tea report, which claims new research has found the presence of green colours in workspaces and living areas can help boost positivity and productivity.
Mike and Gatsby are current TOWIE castmembers. The last time we saw Mike on screen, he was clashing with co-star Chloe Meadows. She was angry he'd retweeted unflattering comments about her, while he wasn't happy about remarks Chloe made about his close friend Kate Wright.
Meanwhile, the last we heard of Gatsby was he'd just signed a recording contract and was getting ready to record his debut album!
Elsewhere, Charlie left in 2013 during series nine and now has his own blog and magazine column, offers fitness and nutrition advice, and works with several charities. Nicole, meanwhile, was included in the series 17 official publicity photos but didn't have any major storylines last series.