Well I am no expert but I like wearing a grenadine with slacks and a v-neck wool pullover and I think it works as a casual tie.
Next thing on my list is a 9 cm navy cashmere so I will pair it with this jacket...
It is not bespoke. Just, IMHO, a well fitting RTW.
Not sure about grenadines. I've seen them worn mostly with suits, so I thought they were considered formal, but they may be just fine as casual. In any case, I think your outfit would have looked better with a challis, madder or knit tie
Isn't the jacket bespoke? It looks like it.