Flat battery - parasitic draw found and fixed

[Brackers]

My 2003 roadster has suffered from a flat battery if not driven every few days.
First I replaced the battery but the problem continued. To diagnose the problem I disconnected the negative battery lead and connected an ammeter between the lead and the battery. With the ignition off and all doors closed, the car was drawing around 200 mA. I removed every fuse one at a time from the engine bay fuse box,  the fuse box at the passenger side of the dash ("RB3") and the fuse block under the front bonnet. No fuse reduced the draw significantly. The drain remained high. I eventually disconnected the alarm siren which is located in the frunk in the spare wheel storage area. This immediately dropped the current draw down to around 20 mA. I am replacing the alarm siren with a secondhand unit and have bought new batteries for this from eBay. I hope this helps others who might have the same issue.  Here are a few pictures of the faulty siren

[Gaz mr-s]

Well done for perseverance.

[Ardent]

I'd be inclined to leave it out.

[puma2]

  good work to find that out with some patience involved as well 

[Topdownman]

Well done.

Will you be testing the new set up once fitted to see if the problem has definitely gone?

[Brackers]

Yes for sure I will test it. You never know with used parts. Might be as bad as my own failed siren 😂
I will also check the current draw once fitted.