Link 3 and 5, which are under the seat, connect to the fuel relay and ignition respectively - so it does seem like you have some modifications… ?
Fuse 28 on the panel would go to the air con blower … which I’m guessing the Defender doesn’t have? If so then it was empty spot that someone has perhaps used to take a feed from ?
28 would go to this connector through a brown and purple wire
https://www.lrworkshop.com/connectors/defender-2002my/C0786
Then from the connector TSD shared through a brown wire
https://www.lrworkshop.com/connectors/defender-2002my/C0153