Danny McNamara missed out on two cup medals after Millwall cut short his St Johnstone loan.
But the Republic of Ireland U21 defender admits his successful spell at McDiarmid provided the platform for first team football in the English Championship.
Now McNamara (22) is backing another Millwall youngster to further his education under Saints manager and former Lions No2 Callum Davidson.
Teenage centre-back Hayden Muller (19) has followed McNamara’s route north of the border.
And he impressed in a 30-minute run out in Tuesday’s 1-1 friendly draw with Preston North End.
“When Hayden told me there was interest from St Johnstone I just told him to go. It’s the best move for him,” said McNamara, who clocked-up 22 appearances for the Perth side before being summoned back to London by Millwall boss Gary Rowett.
The wingback went on to be hailed the Young Player of the Year at The Den.
And he admits those months at McDiarmid were hugely influential in his career development.
“It’s such a great club with a very good manager,” said McNamara.
“Saints are getting themselves a good player.
“Hayden made a few first team appearances for Millwall towards the end of last season.
“He is so good on the ball, very calm and composed.
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“Hayden is also good at one v one defending. He will be a real asset to St Johnstone, I’m sure.
“He is only 19 and he is still learning.
“I actually think he is good enough to play for Millwall right now but he might not have got as many opportunities as he’d have liked if he had stayed.
“Going on loan to St Johnstone and playing in the top league in Scotland will definitely help him progress.
“Hayden will find he is in a great dressing room. I know the lads will help him settle in.
“Obviously Gary Rowett thinks Hayden will be playing at a good standard otherwise he wouldn’t have sent myself and then James Brown there last season.
“Scottish football sometimes gets looked down on but I know how good it is.
“I really enjoyed testing myself against players like Borna Barisic and Ryan Kent at Rangers.
“But I was up against plenty of other quality players.”
McNamara’s impressive form kept Shaun Rooney on the side-lines until January.
But he was delighted to see the powerful wingback make the most of his chance, scoring the winners in both cup finals to pen his name into the Perth history books.
“I was jealous of the lads watching the finals on tv,” McNamara admitted.
“But Shaun is a great guy and no one was happier for him than me when he got those vital goals in the second half of the season.”