VSEL LS40 Line Source column speakers
Above, a detail from a shot of the Vox Sound Equipment Limited display at the British Musical Instrument Fair at the Russell Hotel, London, 17th-21st August, 1969. The LS40 Line Source column speakers are indicated with an arrow.
Vox Sound Equipment Limited (VSEL) LS40 speakers were generally provided with the late-style tilt back frame devised in 1967 or early 1968 by Jennings Musical Industries. A JMI example can be seen on this page, along with examples of the LS40 dating back to 1963. As can be seen in the picture above, the side struts pass through and protrude beyond the handwheels on the side.
Previously the side struts of LS40s terminated at the wheel. The advantage of longer ones was that the speakers might be supported better when standing squarely upright. Older LS40s could be extremely unstable when they were bolt upright - they were definitely at their best tilted back.
The 10" drivers fitted by VSEL are likely either to have been Elacs or Goodmans.
Detail from the VSEL brochure on PA equipment - "The Communicators". The Line Source units illustrated are the LS15, LS40, and LS60.
A detail from the VSEL pricelist, February 1969.
Below, a set of VSEL LS40s in excellent condition sold by vintage-guitar.de a little while ago. The presence of an XLR connector indicates that units were to be used with valve PA amps. Solid state PA amps had 1/4" jack sockets. The new Line Source units for these were the Focus - see this page.
A set of Line Source 60 speakers issued by "Vox Sound Limited" in late 1970 can be found here.