WW2 No 42 fuse, what was it used for?

I have a WW2 tin box for a “Delay capsule No4” that I assume goes into the No42 mkII fuse, both of which are stencilled on the lid.
It has an unusual locking latch on the box which would indicate that they did not want the box opening prematurely.
I can not find any information on the capsule or the No 42 fuse and wondered if anyone has any information about them.

Was this a grenade fuse for the Mk II “pineapple” grenade??

I am not sure what it was for. My contacts don’t think it was for a grenade.! as the boxes they have for these don’t have the latching catch.

I guessed at Grenade fuse because of the “delay” description and The MkII… I just did a search and find no No. 42 type fuse listed in t e pages that came up. My WAG was not so good. I guarantee that someone on this forum will know.

Fuze Number List, British.pdf (48.1 KB)

Thanks for the list.
It makes me wonder what it was used for as a 15 second delay seems a strange time to have and the special priming also seems strange.
Maybe for an anti aircraft shell???

Thanks anyway. It may be for anti aircraft shells or for some SOE use but these are only a guess. I have just been given a list which says the No 42 fuse had a 15 second delay.

That would have been a “fuze” and not have British nomenclature.

The No42 was as said a 15 second time fuze adopted in 1885 for the 2.5 inch howizer illuminating projectiles.
The delay element was prone to humidity as it consisted of a black powder train. Hence it had to be stored in sealed condition and seals were only to be broken right before the intended use as everything else could have lead to a dud.

Back then the term “fuse” was common as the original term comes from black powder fuzes which were burning.
The term “fuse” remains today for “safety fuse” (still black powder burning).
Often missunderstood today and often the terms “fuse” and “fuze” are confused (almost ambiguous).

It would have contained delay capsules for No. 42 Aircraft bomb fuze.

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Tim, ah, that is the 2nd possibility!

But as we are on it, I was unable to locate any diagram of a No42 “artillery fuze”.
Do you happen to have one?

Hi Tim
Thanks for the heads up and the link.
It would make sense as the box came from the fleet air arm and I assume they would drop the flare on a parachute for it to ignite 15 seconds later so the aircraft would be well clear and not lit up.

Found some pictures of flare bombs which look like they have the No42 fuse on them.
I am not sure if they had a parachute or were just incendiary bombs but why have a delay for a incendiary bomb unless it was just to arm it after 15 seconds.images ![images-1|263x191]

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further picturesimages-1

and more

The No. 42 Fuze was used with - 4.5 & 5.5 inch Reconnnaissance flares, No. 3, 14 & 15 Cluster Containers and 500lb Smoke bomb.

There were two groups of capsules; Type C No. C2 to C5 used when the fuze is required to function within 1,000 metres of the aircraft and the Type C No. C6 to No. C50; the numbers indicate the length in delay in seconds when functioned at ground level.

The No. 42 became the No. 848.

Alex for you -

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Tim, thanks a lot!
I was almost sure you would have it!

Hi Tim
Can you confirm that the capsule box I have would be for the No 42 flare bomb I have shown.



It’s for the No. 42 Fuze (Air/Naval service), not for the No. 42 Land Service Artillery fuze

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Thank Tim