A problem which shows in selfmate form an idea which was exploited
many times in directmates by the Warton brothers.
Solution: The position is a complete block. If the bishop
is neutralised then 2...b4 mate is forced, hence the set
variations 1...Bxc7 2.Rxc7, 1...Rd6 2.Rxd6; 1...Bf6 2.gxf6;
1...Bg7 2.Rxg7; 1...Bh8 2.Rxh8; 1...Bh2 2.Rxh2; 1...Bg3 2.fxg3;
1...Bf4 2.Rxf4 and 1...Bxd4 2.Rxe4. White however has
no waiting move, and the line-clearing key 1.Rdh7 abandons
the set capture on d6, instead exploiting the newly formed black
battery – 1...Bd6 2.Qf7+ Se6. There is a second,
less interesting change, with a different rook capturing after
1...Bh8. The other variations remain as set. The Grab Mutate was
a favourite theme of the Warton brothers, and many examples in
directmate three-movers can be seen in the collection contained
in the Composers section of this site.