UKH

Plenty of big full-size compasses for work or for ML-esque stuff (issued). Never used or tried an orienteering compass but feel it would get annoying on my hand when it's only an occasional need to check a bearing or triangulate in fog/shit weather.

Silva used to do a small, rubberised running compass but discontinued it. 

What can you suggest? 

The other reason I'm not sure about a thumb compass is that it'd get tangled up in pole straps 

You need a certain amount of size, for a compass to be quick and simple to use.  I have a Silva Classic that fits the bill perfectly for me. 

Silva do a mini compass, the RangerSL with a safety pin that can pin to a shirt (or anything else). It's a sighter with a mirror when you need more accuracy, but open it works well for orientation.

e.g. Here...  https://www.bike24.com/p2272842.html

(Not the best UK price but the best photos of it open)

I have a little decathlon one, has a small baseplate and thumb strap.

https://www.decathlon.co.uk/p/orienteering-left-thumb-compass-racer-500-ora...

A thumb compass only really makes sense if you're carrying a map in your hand.  It probably would be annoying otherwise especially if you're using poles, although you can flip one upside down while you're not using it so it sits on the back of your thumb with the plate over the back of your hand if you see what I mean.

Perhaps something like this would be a better bet - similar sort of compass, but could be worn on your hand or wrist instead.  (I've never actually tried one though, so this is not a recommendation.)

https://www.decathlon.co.uk/p/quick-and-stable-wrist-compass-for-multisport...

Can't see that being much use for setting against a map to be honest.

All the OP seems to need is a compass with a smaller base plate to reduce the pack size. Thumb compasses aren't a bad option, they tend to have needles that settle quickly and have a small (if odd shaped) baseplate that's adequate for the job. You don't have to wear in on your thumb, it would sit in one of the small pockets in a race vest for occasional use, and the OP could always remove the thumb strap.

You're probably right, if you were looking for much in the way of precision.

I just suggested this one because it seems to fit the description of what the OP is looking for (and does have the 'fast' needle of a thumb compass I believe).  I think the small Silva running compass that's no longer available mentioned in the OP might be a 424, in which case this is possibly the nearest thing to it that you can easily buy in the UK at the mo.

Edit to add:
Getting a thumb compass but just not wearing it on a thumb does seems like a v good idea though.

https://dash4it.co.uk/silva-begin-wrist-orienteering-compass.html?gclid=Cjw...

You can get wrist and back of hand compasses for mountain bike events that require navigation which leave your hand relatively free. 

Edit... I see I've duplicated basemetals thoughts 

I found one in stock.

https://www.jurassicoutdoor.com/outdoor-equipment/compasses-accessories/sil...

But weirdly it doesn't have any demarcations on it.

I think the £17 cheap 'for kids' Silva Field might be the best option - 28g, rounded edges (won't cut a hole in my pack) and easy in the palm.

The lack of markings is because generally you aren't taking a bearing, you orientate the map to the ground, use the compass side to sight direction of travel, then look down that line to a feature on the ground and run, or keep holding it in position as much as possible and run on the bearing. 

With magnetic variation being very small at present it isn't really necessary to read the berings.

Big difference between +/- a couple we used to do vs being 15 degrees out because there are no units at all on thing

I don't know about you but if I'm running I take the bearing off the map and run on it without even reading the numbers?

A running or orienteering compass is used in a very different way to all out MLesque geekery.

Love my Moscow thumb compass (stable when running and sets fast) if I know I’ll have map in hand…..but most of the time one of these lives in the bumbag -

https://www.decathlon.co.uk/p/begin-100-baseplate-orienteering-compass/_/R-...
 

cheap, tiny baseplate and super light, rugged and when I’ve needed it for a bearing has worked nicely 

For orienteering I use a thumb compass, for anything longer than a couple of hours I take a Silva Ranger.

Buying something that's used differently (e.g. thumb compass) from Decathlon means you won't spend loads of money just to find out that it's not the solution for you.

Nothing even a tiny bit geekery about having a bearing ring on a hand help compass.  You don't have to use it. I seldom do, either when running or walking. But it's there if you do need it, weighs nothing and adds function to a valuable tool.  Took about 3 minutes to teach my daughter how to take a bearing

It would certainly be possible to add it but a small thumb compass is still a very different tool to a full size baseplate compass.

If I think I am going to be doing the sort of navigation that would benefit from reading the numbers I have to carry either a bigger compass or a pair of glasses

In all honesty I leave my compass in the bottom of my pack when I run, and just orient using contours/journey knowledge. If it comes out it’s because I’ve f*cked up an ML geekery is needed. It’s also handy to have a number to share with the person/people you may be running with when this happens, so it’s nice to have units. But not to the degree where the old +- 2 degrees of magnetic variation ever mattered, which is what was mentioned in the post I was replying too.

IMO and for my use-case, units are nice to a 15 degree resolution, anything else is excessive.

You can get baseplate compasses with an orienteering style needle. I'm a fan of them. If you are thinking of doing an MM or something similar, you'd want one with the degrees on it so you can share bearings with your partner. If not, like has already been mentioned on here, I don't look at the numbers.

That Decathlon thumb compass has a bearing ring so you can use it for both regular nav with bearings or orienteering style map setting.

I have one, it's a good bit of kit, a fair bit cheaper than a Moscow thumb compass and more versatile.

They are a great bit of kit.

It was a bit of a problem until I remembered that I had bought the left land version. I almost dislocated my shoulder in my  contortions to make it work on my right hand 

TBH a Silva Classic baseplate is cheaper and does what the OP wants, if he's not desperate for a thumb compass.