A compass aligns itself with the magnetic lines around the earth. This doesn't mean it is pointing to true north (N90.00). To find true north this compass indication must be adjusted for magnetic declination and/or variation. But as mentioned already the magnetic fields are variable around the earth.
To give you an indication where the isogonic magnetic lines are see the pdf below.
US/UK World Magnetic Model -- Epoch 2005.0Main Field Declination (D)