Sidleen rim nightlatch and Ingersol connection

[chubbbramah]

This is the apparently uncommon Sidleen nightlatch: has anyone else seen one in service?

[chubbbramah]

I can no longer remember where I found the cylinder shown on the right. It has evoked some interest at shows, as it is an early cylinder without the steel cover. Additionally, it has only 2 fixing screws.
Soon after the Impregnable cylinder appeared, one was subjected to an unforseen attack. This was countered by adding the domed steel cover. And 2 additional fixing screws were added, as on the left cylinder. It was found that many decorative finishes did not last well when applied to the hard steel cover, so the range offered was reduced.

Just noticed I have been mis-spelling throughout: should be Ingersoll with 2l's.

[Huw Eastwood]

I can no longer remember where I found the cylinder shown on the right. It has evoked some interest at shows, as it is an early cylinder without the steel cover. Additionally, it has only 2 fixing screws.
Soon after the Impregnable cylinder appeared, one was subjected to an unforseen attack. This was countered by adding the domed steel cover. And 2 additional fixing screws were added, as on the left cylinder. It was found that many decorative finishes did not last well when applied to the hard steel cover, so the range offered was reduced.

Just noticed I have been mis-spelling throughout: should be Ingersoll with 2l's.

c1947~52 as I'm pretty sure it was late 1952/3 when the design changed as a result of a spate of London burglaries in the late 1940s.
There's actually quite a story behind it which pushed Jack Taylor to revise the original exposed cylinder/plug design, and add the additional armoured rose.

The design changed a lot from the original and the differences are quite noticeable if you take one apart and compare them with a later example like your photo.

• The sidebars were originally unsprung. The brass housings had distinctive internal annular grooves in the back face to guide a projection off the floating sidebar. This feature was changed in favour of a sprung sidebar with ramp action and without the guide grooves in the housing.
• The housings were originally solid brass and clearly marked 'top' to facilitate correct installation. Later changed to zinc alloy die-castings.
• The Levers were also solid brass which were later changed to nickel silver.
• The cylinder plugs were 2-part with very
  thick solid-brass fronts, later changed to the one-piece zinc alloy die-castings with thin pressed-on caps.
• Two threaded fixing lugs only (as already mentioned), later changed to four.
• Also (as already mentioned) the exposed cylinder fronts were covered by an additional armoured rose as a result of the spate of successful attacks on the locks in the late 40s.

The story behind the burglaries which prompted the Ingersoll design changes is out there somewhere, it's definitely worth a read if you find it.