Handlebar clamp sizes - does it matter?

[Ajax Bay]

Have you looked at what SJS offer

Thank you. I'd checked about 6 others. Silver thobut. One reviewer is pleased it can 'take a bell'!
https://www.sjscycles.co.uk/stems/g...1-inch-quill-to-1-18-inch-threadless-adaptor/
Have been hunting for a (newfangled) stem I know I've got (somewhere) before buying it (and some bars).

 

[Ajax Bay]

I have taken your (plural) advice (for which many thanks) and bought the following (from CRC):
1 X FSA Vero Compact Road Bar
Black, 42cm, 31.8mm, sku122513
£22
1 X Brand-X Road Stem
Black, 90mm, 31.8mm, 1.1/8" sku428480
£10
Brand-X Quill Adaptor Alloy
Black, 150mm (minimum insertion 70mm)
Save 60% sku21327
£8

The Nitto bar (25.4mm clamp at its centre, matching my current quill stem) was the other sensible option but I decided to take advantage of necessary change to choose compact bars and move them slightly closer.

 

[Milkfloat]

These are cheaper , the new teeth could be expensive though.

 

[DCBassman]

Brand-X Quill Adaptor Alloy
Black, 150mm

That's exactly what I've just received for the Trek revamp.