One of those which can win matches

Playing a team match, you pick up this lovely collection:
♠ A54
♥ Ax
♦ x
♣ AT98xxx
You're in 3rd seat, V vs NV, and you're playing a light opening system. The bidding starts:
pass - 1♦ - ?

I guess most will bid a simple 2♣. Bidding any higher with 3 Aces and such distribution is quite useless. So we continue:
pass - 1♦ - 2♣ - pass
2♠ - 3♦ - ?

Now what?
I know partner has less than 10HCP, and I thought partner had a good ♠ holding, and probably some ♣ tollerance as well. Since I have such control over all the suits, I decided to just bid 4♠, my partner can bring home tight contracts.

Here's the full hand:
♠ QJT9x
♥ KQxx
♦ QTx
♣ x

♠ A54
♥ Ax
♦ x
♣ AT98xxx

The play was quite easy, and we made 11 tricks. The other table didn't find 4♠ so we won bigtime with this board.

My partner decided not to open 1♠ with 10HCP although we usually open 5 card Majors with 10-14HCP with very few exceptions. I guess he didn't like his slow values, although he has both Majors and no bidding problems can occur. After a 1♠ opening I think I'll start slow but we'll still end up in 4♠.
I don't know why opponents didn't find it...