Shimon was born on July 14, 1923 in Dnipropetrovsk (now Dnipro, Ukraine), to Eliyahu and Hina Gita, twin brother of David. In 1925, the Lokshen family made aliyah to the Land of Israel and settled in Tel Aviv. He studied in the Tel Aviv’s Commercial High School (now the Geula School). He joined the Maccabi Tel Aviv movement and excelled in sports, especially as a basketball player.

In 1938, he joined the IZL, and like most his age, he was sent to put up posters and disseminate promotional materials, surveil and participate in other missions. Later, he underwent firearms training. When IZL split, he joined Lehi. The underground was pursued by the British authorities, assisted by many from the Yishuv, so that the names of many IZL members fell into British hands, leading to Shimon’s arrest on May 12,1942 four months after the murder of Yair. He was interrogated and sent to Mizra, based on the Mandate’s emergency procedures. After Yitzhak Shamir and Eliyahu Giladi fled from Mizra, the British moved the detainees to Latrun. When twenty Lehi members escaped via a tunnel they dug from one of their sheds, the British exiled 251 IZL and Lehi detainees to Africa on 19 October 1944, Shimon among them.

He was held in Sembel (near Asmara, Eritrea), Carthago (Sudan), back to Eritrea, and then to Gilgil (Kenya). He is remembered as having a good heart, being social, pleasant and friendly. Throughout the years of his detainment, he continued playing sports and encouraged other detainees to join him.

Shimon was returned after the State of Israel was established, on 12 July 1948, after more than six years of detainment in the Land of Israel and abroad.

After the War of Independence, Shimon started working for the construction firm BeAhdut Koheinu, partly in Jerusalem. Later he worked for a car rental company in Malchei Israel Square in Tel Aviv. After it closed, he moved on to the Koppel car rental company, where he worked until his last day.

Shimon died of a severe illness on 4.11.1986, at age 63. He was buried in the Holon Cemetery.