Playing a strong ♣ system with 5 card Majors, 1♦ shows 11-15 with no 5 card major and a hand without a winner in 3 suits and 4 tricks (which would be 1NT).

With this in mind, I open 1♦ (alerted).  Ops overcall 1♥ and partner bids 1NT (up to 10 HCP for us).  The auction is then passed out.

After the ♥ lead and partner wins the 2nd ♥ in hand, the K♦ is led and loses - back in and lose another ♦ - is this worth it?  YES!!!!  Make use of dummy's long suit, doing so now sets up the long suit.  It may seem that the ♠ would offer more tricks but these come at the end.  Perfect play earns my partner 100% for making 8 tricks - it is not just the 7NT hands that count, this is duplicate pairs and every hand counts, this was great play and well done partner!