Published: 12:50 BST, 2 May 2016 | Updated: 18:07 BST, 2 May 2016
He branded her the 'love of my life' on numerous occasions throughout their stint on Made In Chelsea.
And Caggie Dunlop proved she and former love interest Spencer Matthews are still closer than ever as they celebrated her 27th birthday together at The Ivy Chelsea Garden eatery in London on Sunday afternoon.
Joined by a number of their former co-stars including Millie Mackintosh, Rosie Fortescue and Hugo Taylor, the pair seemed in good spirits as they cosied up to each other and enjoyed the Bank Holiday sunshine at the King's Road hotspot.
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Birthday girl: Caggie Dunlop celebrated her 27th birthday at The Ivy Chelsea Garden in London on Sunday alongside her Made In Chelsea BFF Millie Mackintosh (pictured) and former love interest Spencer Matthews
Closer than ever: Caggie - who left the E4 reality show back in 2012 to pursue a career in the music industry - hailed Spencer, 26, one of her 'favourite people of all time' as they cuddled up for a cute selfie
Caggie - who left the E4 reality show back in 2012 to pursue a career in the music industry - hailed Spencer, 26, one of her 'favourite people of all time' as they cuddled up for a cute selfie.
Beaming into the lens, the pretty blonde looked the picture of happiness, while ladies' man Spencer gazed adoringly at his former flame.
Alongside the snap, she wrote: 'One of my favourite people of all time. 12 years of friendship and still going strong. Thanks for making my 27th so special.'
It's little wonder Spencer looked so besotted, with Caggie looking the epitome of boho beauty in a pink and white floral bardot dress, which she teamed with an oversized stonewash denim jacket and shades.
See Made In Chelsea updates as Caggie Dunlop cosies up to Spencer Matthews
Ladies' man: Lovesick Spencer (pictured leaving the King's Road eatery) previously described his brief liaison with 'childhood sweetheart' Caggie as one of the 'happiest moments' of his life
Former I'm A Celebrity... Get Me Out Of Here star Spencer - who recently briefly dated Geordie Shore's Vicky Pattison - kept things casual in skinny jeans and a grey tee, which he teamed with a charcoal tailored jacket.
But Spencer wasn't the only Made In Chelsea chum Caggie paid tribute to on her special day.
The star shared a funny montage of flashback snaps of her and Millie Mackintosh over the years, alongside the caption: 'To me and the mac @milliemackintoshofficial I love her always and forever #sillyandbilly.'
Millie made a quick exit from the bash, holding hands with birthday girl Caggie as she strutted her stuff in a black pinafore minidress and white lace top.
A rose between...: The pretty blonde later posed for another snap with Spencer and his best friend Hugo Taylor, who has recently been linked to Caggie's BFF Millie Mackintosh in the wake of her marital split
The newly-single designer - who split from rapper husband Professor Green, in February after two-and-a-half years of marriage - was no doubt keen to keep her head down, given that she'd spent the afternoon with ex-boyfriend Hugo Taylor.
Millie and Hugo have been linked on numerous occasions in the wake of her marital split, and were pictured getting cosy at British Polo Day in Dubai in March, before spending the night together at her London home a mere matter of weeks later.
The first few series of Made In Chelsea documented the ups and downs of Spencer and Caggie's romance, with Spencer unable to hide his feelings for his blonde pal in spite of the fact that he was living with then-girlfriend, dancer Funda Onal.
Although Caggie initially rejected the hotel heir's advances, she eventually succumbed during a group holiday to Finland, when the couple finally slept together.
Gal pals: Millie made a quick exit from the bash, holding hands with birthday girl Caggie as she strutted her stuff in a black pinafore minidress and white lace top
Lovesick Spencer later described the liaison with his 'childhood sweetheart' Caggie as one of the 'happiest moments' of his life, despite her later rejecting him once again.
In an interview with Closer magazine back in 2012, Spencer said: 'I would never discuss the finer details of what happened, but it was the most amazing three days and getting together with her was one of my happiest moments to date.
'When we sealed the deal in Finland it was very special, but we drifted back into being friends straightaway. I'd like to say I was in love with Funda and Louise and lots of girls I've dated, but none of them have made me feel like I did for Caggie.
All the crew: Millie and Caggie's co-star pal Rosie Fortescue was also in attendance at the bash
'But she obviously doesn't feel the same. If she did, then we would have been together by now. But from a young age, I always assumed we would get married - so never say never. She's my childhood sweetheart.'
Spencer has had long-term relationships with numerous Made In Chelsea stars, including Louise Thompson, Lucy Watson, Stephanie Pratt and, most recently, Lauren Hutton.
Caggie most recently dated businessman Scott Sullivan, the ex-boyfriend of glamour model Katie Price.
Best friends forever! Caggie also posted a photo montage tribute to Millie, full of hilarious snaps of the pair throughout the years