Grand Slam Conversion

White to play and mate in two moves
 

a

b

c

d

e

f

g

h

  

8

 8

7

 7

6

 6

5

 5

4

 4

3

 3

2

 2

1

 1
 

a

b

c

d

e

f

g

h

  

Solution

  1. d6+     Kd7 (Kf8 2. Qf7#))
  2. Qe6#

 

For an extra 2 bonus points what is wrong about this position.

There are three white knights and two white bishops on "white" squares requiring two pawns to be promoted.  But there are seven white pawns on the board and therefore two pawns could not have been promoted.

Our thanks to

Olivier RONAT (France)