Benchmarks added to OS Maps

While we’ve already celebrated the 25-year landmark since the last traditionally-cut benchmark was carved, we thought we’d carry on the merriment by adding them to OS Maps!

Yes, you heard right. So if you’re an avid benchmark bagger or just intrigued by geographical history, you’ll be delighted to know that, instead of downloading our benchmark archive, you can simply find them on OS Maps desktop. Not only that, but when you click on the specific benchmark, it will tell you which one it is and when it dates back to!

Screenshot of a benchmark on OS Maps near our HQ in Southampton.

What is a benchmark?

Have you ever seen one of these when you’ve been out? If so, you’ve seen one of our benchmarks. Although benchmarks have been around for a very long time, many are surprised when they find out they’ve been about much longer than our renowned trig pillars. While trig pillars were used in the National Grid as accurate fixed points for mapping coordinates, benchmarks were fixed points which were used to calculate heights above the mean sea level.

Benchmark image from Instagram @spikes68

Benchmark captured by @spikes68 via Instagram.

What’s in a name?

These horizontal marks were used to support a stable ‘bench’ for a levelling stave to rest on – hence the name ‘benchmarks’. This design ensured that a stave could be accurately repositioned in the future and that all marks were uniform.

How many are there?

While there were over 500,000 benchmarks cut, this number is unfortunately dropping as roads change and buildings are demolished. They are largely concentrated in urban areas and mostly along roads or on the side of buildings and walls. Greater London has almost 18,000 benchmarks as well as large clusters in Leeds, Bradford and Birmingham as you can see below.

Example of benchmarks identified on OS Maps.


Now before you go bagging your benchmarks, we must remind you that some benchmarks may not be there any more and some may be on private property – we do not condone trespassing! Additionally, please note that as this benchmark feature in OS Maps uses an archive database, it isn’t updated when benchmarks are no longer in existence.

Find out more about OS Maps and follow us on Twitter for the latest.

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16 Responses

  1. Justyn Holmes

    I’m looking for some help, there is one of these benchmarks on the bridge over Jocks burn at NS 83781 50040 which I was showing the children whilst out and about on a local walk. However I can’t find it on the benchmark download or in the OS maps. Could you let me know which map I have to look at to see this information?

  2. Rosemary Yallop

    I would like some help in finding out about a local benchmark which appears on OS maps as early as 1888, again in 1906 and possibly later. It is not listed in the archive spreadsheet nor on your helpful bench mark map.
    Could you please tell me where within OS I can address my question and send details? Is it the customer service e-mail address given above?
    Many thanks

  3. Gary Cooles

    Adding details of OS benchmarks to the desk version of OS Maps is brilliant! Are there any plans to adds it to the mobile version of OS Maps? I’d like to be able to search for them on my mobile whilst I am on a walk. Or even when I’m cycling with my Trail2 GPS. Thank you!

    1. Jocelyn

      Thanks for your input Gary, we will pass your suggestion on to our product team for their consideration. Many thanks, Jocelyn

  4. Matthew Terry

    I’ve been trying to find some information about a benchmark I’m luckily enough to have carved into my cottage that appears on old 18** maps. Specifically when it was first carved. I tried looking on the OS Maps desktop (admittedly on a free trial) but it doesn’t appear.
    Location is SH 29963 29006
    Any help would be much appreciated.

  5. Mr Daniel E Farnes

    Was that symbol used by others to create their own benchmarks? I think I found 6/7 in such a small area, some from the National Rivers Authority and the GPO as it does seem alot for the OS alone!

    1. Jocelyn

      Daniel, the OS benchmark symbol is made up of two parts – the Government ‘broad arrow’ and topped with the ‘bench’ to which the height is measured. The ‘broad arrow’ or ‘Crow’s foot’ has been widely used to mark Government property for a great many years, by a variety of departments, in particular the Board of Ordnance, the War Department and the MoD, but also GPO. There is plenty of information available on the internet about its use, see https://eur01.safelinks.protection.outlook.com/?url=https:%2F%2Fen.wikipedia.org%2Fwiki%2FBroad_arrow%23:~:text%3DA%2520broad%2520arrow%252C%2520of%2520which%2Cgovernment%2520to%2520mark%2520government%2520property&data=02%7C01%7CJoss.Harris%40os.uk%7C24c5cb15ed88468f2db908d858a66e6a%7C7988742dc5434b9a87a910a7b354d289%7C0%7C0%7C637356819117216602&sdata=znxR06E5ilNB1Ay17twtz%2FT6p3S%2B8p%2BeYZxdGWUPFBw%3D&reserved=0 for an example. Hope this helps, Jocelyn

  6. Karen Wardley

    I’ve looked at the OS spreadsheet to try to date benchmarks on some Hampshire churches, but couldn’t find a key to the column headings. Does Verified Date mean the date when the mark was made? And to what do the letters and numbers in columns E-G refer to please? Thanks!
    I found it hard to find sites on the spreadsheet but will try the search facility mentioned in the comments above.

    1. Jocelyn

      Karen, thanks so much for your query. As our response includes a couple of images, I will email our reply over to you via the email address you have used for your WordPress account – I hope this is okay? For your reference, the email address it will be coming from is joss.harris@os.uk. Many thanks, Jocelyn

  7. Anne

    The addition of benchmarks to OS Maps online is excellent, but it doesn’t seem to show fundamental benchmarks. Why is this? Will they be added soon?

  8. Sara

    I am trying to interpret the description of bench mark locations – especially ANG and FACE. Can you interpret for me, please? Any help appreciated

    1. Gemma

      Hi Sara

      The face and angle relate to locations on the buildings etc. For example: “NO 4 THE BUNGALOWS PILDACRE LANE E FACE 2.7M SE ANG” – the benchmark is on the east face of the building 2.7m from the south east “angle” i.e. the corner.

      I hope this helps.

      Many thanks

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