Here is an economical example by the German miniaturist.  The key 1.Qa2 threatens 2.Qg8 and black can defend by blocking the wQ's path at d5.  However, the bB and bR interfere with each other on this square giving the Grimshaw interference.  

1...Bd5 2.Qa3
​1...Rd5 2.Qa8

 
Now we have perfection on a chess board.  This is probably one of the most famous chess problems ever composed.  We have a triple Grimshaw: 3 pairs of interferences between different line moving pieces.  The problem is a complete block and the waiting key 1.Bb3 holds the block.  There are Grimshaws on the squares b7, f6, and g7.  







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Another Loshinski masterpiece.  The wR on f1 is out of play and signals that it may be the key piece.  The key 1.Rb1 makes the nice line closing threat of 2.d4 by guarding the wS on b4.  Black can defend on b2 by closing the line of guard.  This leads to the first Grimshaw:

1...Bb2 2.Qf2
1...Rb2 2.Qxc3

Black can also close the 4th rank at g4 leading to the second Grimshaw:

1...Bg4 2.Bg1
1...Rg4 2.Se6

Finally, Black can block the wB's guard on c4 by cutting the line at e6:

1...Be6 2.Bd6
​1...Re6 2.Sd7

A wonderful problem.  My favorite part is how the composer worked in the Grimshaw defenses to defeat the threat.
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A beautiful changed double Grimshaw that won first prize in The Problemist.  The waiting try 1.e5? (-) yields the play:

1...Bc7 2.Qc8
​1...Rc7 2.Qd8
1...Bf7 2.Re7
1...Rf7 2.e6

but falls to 1...Be6!  The key 1.Qe5 changes all of the Grimshaw mates

1...Bc7 2.Bc8
​1...Rc7 2.Rd8
1...Bf7 2.Qe7
1...Rf7 2.Qe6

A clear rendering of a white Grimshaw.  The try 1.Bc3? threatens 2.Qa2 but is defeated by 1...Se5 because the wB closed the wRs guard on c6 hence 2.Rxe5 will not work.  Likewise the try 1.Rc3? also threatening 2.Qa2 is defeated by 1...Rc7 because the wR closed the wB's line to d4 hence 2.Sxc7 will not work.  What remains is 1.Rc4 making a different threat 2.Sc3.  

Here's something new.  The problem is a helpmate duplex meaning that it has two solutions: one which is a normal helpmate with Black moving first and cooperating with White to mate and second solution in which White moves first and cooperates with Black to mate.  Here we have a concept called Black/White Correspondence in the sense that they mimic each other.  In the two well-matched solutions there is a Grimshaw between the bR and a wB!  Here are the solutions:

B: 1.Rd5 Bf8 2.Ke6 Rd6
W: 1.Bd5 Rc1 2. Kd4 Bc4

Here is my only problem (so far) that contains a Grimshaw interference.  The Grimshaw is not the point of the problem rather it happens in the by-play.  See if you can find the three tries - moves that are foiled by a single black defense.  I'll post the solution after it has been published.  

Here is one of my personal favorite compositions.  Although this was an earlier problem, it was a great stepping stone for me in terms of complexity.  Notice there are set capture mates for the bQ's moves to c4,d4, and e4.  The wP on d2 is out of play but offers the try: 1.d4? which guards e5 threatening 2.Se7 as well as guarding c5 and closing the bQ's line, hence also threatening 2.Qb3.  However 1...Qe3 defeats this try.  Since this is not the key it is obvious (from the wPd2 and wRh4) that key might give the bK a flight at d4.  Now lets try moving wBc5 which generates the threat 2.Qc5.  Moves along the diagonal c5-f8 are defeated by 1...Bg1.  Moves along the diagonal a7-f2 make a double threat of 2.Qc5/Qc6 but are defeated by 1...Qc4 because of the flight for the bK on d6.  What remains is the ideal key move of 1.Bd4! which only threatens 2.Qc5.  A good key does one of 3 things: grants flights to the bK, sacrifices a piece, and allows Black to check.  This key does all three!  Plus the play is some of my best stuff with cross-checks, self-pins, and self-blocks variations:

1.Bd4! (2.Qc5)
    1...Kxd4+/Kd6+ 2.Bf5
    1...Qd6 2.Qb3
    1...Se6 2.Bc6
    1...Qxd4 2.Qc6
     
   

Here's a lightweight favorite of mine.  Again a R+B battery is set up but controlled by bBh7.  The key 1.Kd6! moves the wK right into harms way and gives the bK two flight squares.  However checks by the bR interfere with the bB allowing the battery to fire: 1...Rd3+ 2.Bd5 and 1...Rg6+ 2.Be6.  The key also grants two flights and has beautiful by-play: 1...Kb6 2.Bc2, 1...Kb4 2.Kxc6.

Here is a tour de force again by Anderson.  The problem allows  five cross checks and has a flight granting key!  The key 1.Qb6 guards d4 after the threat 2.Se4.  

   1...Sf~+ 2.Se4 (threat)
   1...Sxd6 2.Sd3
   1...Sd4 2.Rf5
   1...exf6+ 2.Sb7
​   1...exd6 2.Rd4

​Here is a beautiful problem from one of my favorite composers.  Again the wK walks into a barrage of checks from black batteries.  The composer uses the half-pin mechanism and wonderful battery play to handle the checks

1.Kf7! (2.Qb8)
   1...e5+ 2.S7d5
   1...Bg5+/Bg7+/Bh8+ 2.S3f5
   1...Be5+ 2.S7f5
​   1...Bxe7+ 2.Bxf4

Here is a wonderful problem that was selected as one of the top 100 problems in the book A Century of Good Companions Two Movers.  In the set play the bQ can check on b5, e5 and h5 which are met by

   1...Qb5+ 2.Sc6
   1...Qh5 2.Sf7
   1...Qxe5+ 2.Sxe5

However the key unguarded c4 and closes the wRa5's line changing all three of these mates.
 
1.Sc5! (2.Se6)
   1...Qb5+ 2.Sed7
   1...Qh5+ 2.Sg6 
 
Finally 1...Qxe5+ is met by the threat.

Even though we have devoted a whole blog post to Mansfield's cross-checkers we have to include this one.  The pinned bS on f3 is preventing any checks from Black.  Surely the key will not unpin this knight...nope, that's exactly what it does and three cross checks follow.  And like so many of Mansfield's problems the key grants a flight to the bK.  Notice the correction play by the newly unpinned bS.

1.Se4! (2.Rc5)
   1...Sf~+ 2.Sf5
   1...Se5+ 2.Sf6
   1...Sxd4+ 2.Sf2

I'll leave it to you to work out the by-play

Finally we end with a masterpiece from Gamage.  The key 1.Bb4 enables Black's Q+B battery to fire at the wK.  What transpires is  a thing of beauty with a full use of the half pin.

1.Bb4
   1...Bxf3+ 2.Qf5
   1...Bc6+ 2.Sc5
   1...Be4+ 2.Se5
   1...Bxe6+/Bc4+/Bxb3+ 2.Sg5

I'll leave to you to work out the other half-pin the variations by  the bBd4.