|Date of birth||14 May 1934|
|Place of birth||Cumnock, Scotland|
|1957–1965||Scottish League XI||14||(1)|
|* Senior club appearances and goals counted for the domestic league only|
This section relies largely or entirely on a single source. (August 2017)
He signed for Rangers in 1952 and made his debut on 12 September 1953 in a 4–2 win over Ayr United at Ibrox. He made a total of 13 appearances in his first professional season with Rangers and continued to make progress the following season, playing in 12 of Rangers' 41 matches.
By 1955–56, Caldow had become a regular in the Rangers team, making 35 appearances, mostly at right back, as Rangers won the League title for the first time in two seasons. Rangers retained the League title the following season, 1956–57, and Caldow was once again an important member of the team, making 40 appearances, this time mostly at left-back. He won his first Scotland cap against England on 6 April 1957 in a 2–1 defeat at Wembley.
Caldow continued to be an integral member of Rangers' team, featuring 49 times in 1957–58, including four European Cup matches against AS Saint-Etienne and AC Milan. Caldow also played in all of Scotland's three World Cup matches against Yugoslavia, Paraguay and France. After finishing third that season, Rangers regained the League title in 1958–59, with Caldow missing just one match.
Caldow won his first Scottish Cup medal in 1959–60, and despite failing to retain their League title, Rangers reached the semi-final of the European Cup, defeating Anderlecht, Cervena Hviezda Bratislava and Sparta Rotterdam before eventually losing to German club Eintracht Frankfurt.
European success continued for Rangers the following season as Caldow captained Rangers to the inaugural Cup Winners Cup final, defeating Ferencváros, Borussia Mönchengladbach and Wolverhampton Wanderers before losing 4–1 to Fiorentina in the final. Caldow missed just one game that season as Rangers also regained the League title and won the League Cup.
Rangers again failed to retain the League title the following season, 1961–62, as surprise package Dundee edged out Rangers by three points. However, the League Cup was retained and the Scottish Cup was also won as Caldow played in 52 of Rangers' 58 matches. Rangers also impressed once again in Europe, reaching the quarter final stage of the European Cup, where they lost to Belgian club Standard Liège.
Caldow's fifth and final League championship medal came in 1962–63 where he also won another Scottish Cup medal. That season also saw the end of Caldow's international career, after he suffered a broken leg in three places in a 2–1 win against England at Wembley, following a tackle from England's Bobby Smith.
Following a long rehabilitation program, Caldow made only four appearances in 1963–64, however, he re-established himself the following season at left-back playing 34 matches helping Rangers to a 2–1 League Cup final success against Celtic. Rangers in Europe reached the quarter-final of the European Cup where they lost 3–2 on aggregate to Inter Milan, despite winning 1–0 at Ibrox. It was a disappointing season for Rangers overall, however, as they finished in 5th place in the League with Kilmarnock finishing top.
1965–66 proved to be Caldow's last season at Rangers and he made only three appearances, the last being a 3–2 defeat to Falkirk on 9 March 1966. During his 13 years with the club, he made a total of 407 appearances and won 40 caps for Scotland, 14 of which as captain. Caldow also appeared 14 times for the Scottish League XI.
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After leaving Rangers, Caldow then played for one season with Stirling Albion before moving south to become player-manager of Corby Town in 1967. He returned to his native Ayrshire to become manager of Junior side Hurlford United in 1970.
In 1973, he was appointed manager of Scottish League side Stranraer. Caldow left Stair Park in 1975 and his last involvement with football was as a scout for Queens Park Rangers. He was inducted to the Scottish Football Hall of Fame in 2007.
- "Scotland FL Players by Appearances". Londonhearts.com. London Hearts Supporters' Club. Retrieved 27 November 2011.