Opportunity in the Auction

I enjoy finding opportunities to use free bids to introduce both a fit and another important feature of my hand. One came up this weekend in a sectional pair game. My partner opened a red/white 3 Hearts in 3rd seat. My RHO overcalled 3 Spades. My hand was:
xx
J9x
AQTx
Qxxx
I was comfortable competing to 4 Hearts with these cards, but it would be a gross shot in the dark to act over the 4 Spade bid that I was sure would come on my left. It looked clear to me that 4 Diamonds was the call, both helping partner evaluate his cards and possibly to help us on defense later. LHO did indeed bid 4 Spades, which ended the auction. I led a heart to partner's ace and he promptly returned a diamond into a dummy of:
QJTxx
x
xx
KJTxx
I cashed my 2 diamonds and we eventually conceded the rest, -420. I lamented that we had missed a rare bird, the red on white save. Partner's hand was:
x
AQTxxxx
J9xx
x
Sacrificing would have netted -200 or +50 if the opponents had competed further. In the recap, though, we scored 28/38 for -420. Apparently many had returned their singleton club after winning the first trick with the ace of hearts, allowing declarer to hold his diamond losers to 1. I was pleased with the result and am glad to get rewarded for making bids like this that have several ways to win and very little to lose. It's a standout if you think about it, but it is very easy to lazily bid 4 Hearts at the table.