Have you heard about Post Office Cats in Britain? They are mouse hunters. The post office has actually employed cats since 1868. They are not employed to sort or deliver mail, of course, but to protect the mail and keep the population of mice under control. They make sure your morning post arrives free from damages caused by rats and mice. London post offices were the first to try out the experiment. Within a few months the population of mice had _ sharply. Other post offices all over the country were soon using cats in the war against rats and mice as well. Within ten years the pay of the cats was improved from one and a half old pence a day to six or nine pence a day. Now the average rate of pay is about a few pounds a month. Some of the hard-working cats have become quite famous. In 1980, a cat named Lucky stopped an attempted robbery in a Worcestershire post office on her own. As the two burglars made their way in through the window, Lucky started an attack and they fled empty-handed. Another excellent cat was Jerry, of Earls Court post office in London. He served the building for 16 years and was on duty for 24 hours every day. He drove all the mice away. However, there are fewer cats employed by the post office than at any time in the past. With the faster movement of the mail and better surroundings, post office cats are not always needed. But many post offices still employ them and they become great friends with the postmen. According to the post office, there is no plan for their services to be discontinued in the foreseeable future. The cat named Lucky became famous because  _  .
She served the post office for 16 years around the clock. She alone drove two burglars away from the post office. She protected mails from being bitten by mice. She was employed to sort and deliver mail.