Heather Mills MCCARTNEY will have to drop her title of 'Lady' when she divorces former husband Sir Paul McCartney. The former model, who is being divorced by the ex beatle on grounds of "unreasonable behaviour", is reportedly planning to revert to her maiden name after the split is final. But the move will see her lose the title she was given when she married MCCartney, who was knighted for services to music in 1997. The only way she can hang on to the honour is by keeping her estranged husband's name. A Cabinet spokeswoman says, "When a Sir divorces his wife she is allowed to use the title Lady but only if it is in the middle of her name. "So Lady Heather will be called Heather Lady Mills MCCartney. "But if she reverts back to her maiden name or remarries then she will not be allowed to use Lady at all."