The only place Rootes used rivets, and not on a Series 1 either, was attaching the Vin number and data plates on later cars.
HTH,
Steve
I believe Rootes also used rivets to hold on the chrome strips around the grille on all the cars, and on the Tiger, the side trim strips. There are also some rivets in the heater and vent assemblies and on the seats and some interior trim items. But the body rivets shown in the picture are absolutely not original.
As for the glass filter on the booster, it's not connected to the brake lines. It looks like someone added an extra filter to the fuel system, and happened to find a handy mounting flange by using the booster's bracket. If you look, that filter gets the fuel pipe from the tank, passes it through and then down to the motor's fuel pump (with another glass bowl and screen). I suspect it was added due to the Alpine's notorious gas tank paint delamination issues, and I think at this point it could simply be eliminated. Just route the tank line directly to the pump and remove and discard that extra filter.
Other notes:
You should also remove that ungodly siren along with any associated wiring/switches... it's a real beast. Once you do, check and see if it's an original "Wolf Whistle"... it looks like it might be... if so, it's collectible and might draw good money on eBay if cosmetically restored.
The ammeter seems to have tape carefully applied to the lower 1/2... not sure what that's all about - perhaps the inner shield - the one that covers the works and says 'Lucas' - is missing?
The shift-knob, clock and volt meter are not original Rootes-supplied items, but are period appropriate aftermarket items which would have been common in the day. The shift knob is likely from Amco products.
One warning about that shift knob, though... if it's what I think it is, it's made of rather heavy metal, and I'd advise replacing it with a lighter knob... these heavy knobs tend to wear the shift forks in the transmission over time since their weight pulls down on the shift lever. There are lots of other period-appropriate knobs available in lightweight wood or leather with a pretty Sunbeam logo... see eBay... here's one that recently sold in wood:
http://cgi.ebay.com/ebaymotors/Very...015QQitemZ250411489321QQrdZ1QQsspagenameZWDVW
...and one currently for sale in leather:
http://cgi.ebay.com/ebaymotors/Vint...001QQitemZ110384732764QQrdZ1QQsspagenameZWDVW
Both of the ones above are period appropriate. The wood ones on eBay currently by Classic Sunbeam are extremely pretty, but i don't believe they are period appropriate. That being said, anything is better than that heavy metal one you have now.
The luggage rack appears to be an original Rootes item, and in rather good condition - these are fairly rare in this shape... keep it!
The upper and lower dash rolls as well as the door panels (cards) appear to have been re-covered in an incorrect material.
The lighter is non-Rootes, and I'm not sure if it's period correct. Looks too old.
Screen washer reservoir is non-Rootes and is too new to be period correct... easy to replace with a correct unit - they show up on eBay all the time.
Considerable non-original wiring and switches under the dash... need to find out what that all does and possibly eliminate it if you can.
Ignition coil mounting appears wrong to my eye... I had thought S1 had them mounted to the valve cover?
Tools and jack in the boot are not original Rootes items.
There are quite a number of relays, in-line fuses and wiring items in the engine compartment that are non-original and will need to be sorted out and likely eliminated.