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Wartime Grid References

22 Oct 2009 17:09 #1 by Peter Kirk
Wartime Grid References was created by Peter Kirk
The list of bombing ranges I photographed today comes with a 1" map number and a grid ref. How do I convert those to modern ones?

Example: Upton = Sheet 64 Grid Ref 571210
No Amount Of Evidence Will Ever Persuade An Idiot (probably not Mark Twain)

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22 Oct 2009 17:32 #2 by carnaby
Replied by carnaby on topic Wartime Grid References
Any idea roughly where Upton is Peter, as there are lots of them in the UK - or give another example?

Graham
Plan A is always more effective when the problem you are working on understands that Plan B will involve the use of dynamite :twisted:

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22 Oct 2009 18:27 #3 by Peter Kirk
Replied by Peter Kirk on topic Wartime Grid References
Northants by the look of it.
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22 Oct 2009 18:49 #4 by carnaby
Replied by carnaby on topic Wartime Grid References

Northants by the look of it.

I assumed it must be a Cassini reference. Tried the online converter - in reverse. Put in Upton Northants's NGR, then added the 'letters' it produced to get wL571210. It sent me to Watford! There are another 18 Uptons. Can we try something different?

Graham
Plan A is always more effective when the problem you are working on understands that Plan B will involve the use of dynamite :twisted:

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22 Oct 2009 18:59 #5 by Peter Kirk
Replied by Peter Kirk on topic Wartime Grid References
Otmoor - Map = 94 Grid = 019333
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22 Oct 2009 19:20 #6 by carnaby
Replied by carnaby on topic Wartime Grid References

Otmoor - Map = 94 Grid = 019333


This worked Otmoor is near Oxford.

Converter is at www.fieldenmaps.info/cconv/cconv_gb.html

You are interested in the two panels:Great Britain National Grid, and War Office Cassini ('WOFO') Grid

Your problem is that your Cassini references are missing the vital first two letters. This is very common with stuff in TNA I find, so you need to know roughly where the site is, and either get an NGR, or guess the first two letters from this site: www.pillbox.org.uk/methodology/maps.asp

If you have the NGR, then:
Got the NGR for Otmoor = SP5616
Put this into the GB 'National Grid' box of the converter and hit 'convert'
This gave wL007357 as the Cassini reference.
The 'wL' is the magic bit - now change the Cassini numbers to your '019' and '333'
Hit 'convert' - the 'GB NGR' updates to SP 57228 13415 - which is what you need.
Don't do any of this after a drink!

Peter - just got your email - wow - that should keep you busy for an hour or sixty.

Another comment - you may of course prefer Lat /long - the converter will do it.

Graham
Plan A is always more effective when the problem you are working on understands that Plan B will involve the use of dynamite :twisted:

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22 Oct 2009 21:09 #7 by Peter Kirk
Replied by Peter Kirk on topic Wartime Grid References
Graham,

Many thanks for the link and more importantly the explanation. On first look the site makes no sense (also second and third) but I think it should work. Hopefully all will be converted by Spring :)

I also found this helpful as well.

humanities.uwe.ac.uk/Regionhistory/rhcne...rticles/RH5Penny.doc

I have also emailed OS to see if they have a converter, it's there maps after all!
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22 Oct 2009 21:40 #8 by carnaby
Replied by carnaby on topic Wartime Grid References

I also found this helpful as well.
humanities.uwe.ac.uk/Regionhistory/rhcne...rticles/RH5Penny.doc


John Penny is a respected local (Bristol) historian. IIRC Andrew Ayers knows him. He's produced some interesting documents over the years.

It's a useful document Peter. I used his maths in a Cassini to NGR Excel sheet converter a few years ago. Unfortunately it didn't work quite right, and the reason I discovered was that there was a typo between the formula he quoted and the example he gave. i.e.
Formula - to get northing subtract '245' etc etc
Example - he subtracts '254'

Never found out which was correct, as I then discovered the Fielden online calculator (which was a stand alone download then).

Graham
Plan A is always more effective when the problem you are working on understands that Plan B will involve the use of dynamite :twisted:

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23 Oct 2009 12:08 #9 by Peter Kirk
Replied by Peter Kirk on topic Wartime Grid References
I suspect there are typos in some of the 1946 listings as some locations are nowhere near once converted.

As regards Upton I seem to have two different grids for it, both don't seem to end up in the right area.

1946 = 64/571210
1953 = 46/289967

And that is allowing for both Cassini and OS on the 1953 version as it might have been converted by then, though it probably has been copied from earlier documents.
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23 Oct 2009 14:08 #10 by carnaby
Replied by carnaby on topic Wartime Grid References

I suspect there are typos in some of the 1946 listings as some locations are nowhere near once converted..

A couple of years ago NP and I were working on American D-Day Bivouac and Marshalling Camps - (EH now have this information). Between 5 and 10% of Cassini locations were suspect.

Graham
Plan A is always more effective when the problem you are working on understands that Plan B will involve the use of dynamite :twisted:

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