Depends.
I'm 33, and quite capable of acting in a professional manner regardless of apparel. But many colleagues are fresh out of Uni, and smart dress does make a tangible difference to their behaviour, likely a secondary school hangover.
And missed the Friendzone discussion...
It's one of those things. You can't force someone to feel for you in a certain way. Just have the discussion without any kind of scorecard. And respect their decision. If you don't like it, then that sucks for you. You may need to change your overall relationship of you can't accept it. And don't bring it up again. Ever. And certainly don't start keeping a scorecard. When thinking of a future present, do consider how it might be interpreted. Refusal of any gift is considered bad manners in British society, so they'll likely feel obliged to accept. Small, not-too-personal is fine, but don't go for the grand gesture.