I cannot find what should be an easy tool to find...whilst trying to re-tap a casing thread I needed an extension to my M6 tap ideally to go back to my 1/4" drive socket set...but for the life of me I cannot find anythiing suitable. I have a normal tap wrench but thats no good for obviuos reasons, taps vary is square drive size so ideally would like an adjustable version ?. Just like a normal tap wrench has but going back to 1/4" drive ?
  
 

Mauser will these work?
www.cutwel.co.uk/catalogsearch/result/?q=tap+extension

How about a 1/4 in drive socket with an allen key.  For example 3/8 socket with a 3/8 allen key in the hex end.  This leaves the 1/4 in square drive end to grab onto your extractor.

Here is a set, the first four small sizes are 1/4” drive and the next four larger sizes are 3/8 drive.
I usually use a junk cheap brand 12 point socket either metric or standard and it usually grips well enough to cut threads, it kinda makes me go slower and pay careful attention to what I’m doing if it does slip.
www.amazon.com/Lisle-70500-Tap-Socket-Se...a-435960418711&psc=1

Yes Pete but would need several to cover my range of taps, was hoping for an adjustable type

Snag is they are not 1/4" at the tap end

Thanks Lizeec I saw those but really wanted a single tool which would adjust like a tap wrench to suit my range of taps.

One of my tap wrenches is like this  
it wouldn't be hard to remove the bar then drill and tap the end, insert a stud then lock off with a nut.
Another alternative is to modify a flat bit extension.
www.screwfix.com/p/flat-wood-bit-extensi...EfD_BwE&gclsrc=aw.ds

I usually find a 12 point socket that fits well enough.  We have metric and standard sets here still. You might be stuck only with metric

I have a set of 8 pt sockets I bought when I started replacing garage door torsion springs back in the early 90s when I could hardly afford a bundle of diapers, let alone a garage door repairman!  I actually used this recently on my DT400 resto