Not sure, but I think this might be an online OS map nav question that hasn't been asked on here before..
On a paper OS map there's an arrow across the margins to show you where True North is relative to Grid North on that particular sheet, and the same info also appears in the legend.
Looking at the OS map online though (and using the OS website/app to print my own), I can't find that information anywhere.
Googling is no help, because I just find lots of explanations that Grid North, True North and Magnetic North are different (yeah, thanks, I know) - but nothing that tells me what exactly the difference is in any specific place*. Either that or various places I can look up the current magnetic declination in a specific place, which is great, but it's little help relating True North and Magnetic North to each other if I'm looking at an OS map without knowing how either of them relates to the grid.
This is more of an academic question really in my case, as it's only a couple of degrees or so which generally just gets lost in the 'noise' of my sloppy navigation - but still, I'd like to know.
Can anyone point me to a website or something that'll tell me what direction Grid North on the OS map is pointing in a specific spot? Or failing that, perhaps a formula that relates it to longitude or something? Ta.
* - I'm sure we all know this, but to be clear.. because of the projection of the grid, the difference between Grid and True North varies across the country, and from sheet to sheet of the paper OS maps. Grid North is West of True North in the West of the country, and East of True North in the East.
Edit to add: pic.
Post edited at 12:44