Chasing into outside wall mortar for a bell box?

Hi all,
I'm trying to fit an alarm, everything is in and looking good apart from the bell box. The plan was to drill a hole from the outside to the cavity then feed a cable down the cavity only about 2 feet or so and hook it with a wire coat hanger.

Problem - the cavity looks to be fitted with some sort of backfill, and can't get any further than about 6 inches down it. B*gger!

So I'm looking for a plan b! I've got the following options I reckon:

- Install with cable showing on the outside of wall, possibly with some armoured trunking. Not a very professional option?

- Drill all the way through the wall into nicely decorated room and then chase up into the loft on inside plaster. Slight problem with that is the ring main is already chased into that area so would have to be very careful not to hit it.

- Chase the cable the 18 inches or so on the outside wall by removing about 10mm of mortar from between the bricks. Then just remortar the 10mm gap. Best bet do you think?

Cheers for any advice!

Tim

Long drill bit, one hole at an angle, feed through with cable rod/coat hanger. Job done.
1 mtr bits can be picked up cheap now if you only want 2 or 3 holes from them.
Or push the boat out and get a nice SDS one for about £40.00, lasts a lifetime.

Metal conduit is used in professional installs where it is nigh on impossible to get a cable out hidden. Meets regs and can be painted to suit the decor.

Radio bells can be fitted to hard wired systems a few decent ones on the market.

Keep existing holes fish down with cable rods with two people. you will catch the rod eventually.
Your just not used to this and have given up
One of the above will resolve your issue.
Good luck

Using long drill bit , drill up at an angle towards the loft , if it doesnt quite reach use your cable-rods to poke into the loft ( or coat hanger ).

Cheers guys, pretty obvious when you find out what to do! Just need to get hold of a big drill and even bigger drill bit now!

A long thin 6.5mm is best - can use it with a battery drill.

If it's not long enough drill one hole from the outside and one from the inside to meet in the middle.

(I wish).

Trick is two different sized drill bits, larger from one direction drill towards that with a smaller diameter, thus increasing you target size.