Now this is interesting. Instead of looking in the StarAlliance timetable (1st May - 18th July 2010), I've done a quick search on ITA instead:
NCL-BRU
BRU-NCL
for a random date in June.
Seems there are direct bmi regional flights!
Departs Newcastle, United Kingdom (NCL) Fri, June 18 6:25a 1 hr 20 min
Arrives Brussels, Belgium (BRU) 8:45a
1 adult in booking code E, covered by fare (A1) below
Brussels, Belgium to Newcastle, United Kingdom: 383 miles 1 hr 30 min
Brussels Airlines Brussels Airlines Flight SN2187 on an Embraer ERJ-145 (jet) in coach class
(operated by BMI REGIONAL)
(snack)
Departs Brussels, Belgium (BRU) Sat, June 26 9:35a 1 hr 30 min
Arrives Newcastle, United Kingdom (NCL) 10:05a
I note these are given in the drop down destination list on flybmi.com but searching doesn't give any results. You can get fares from brusselsairlines.com though.
Prices seem to be about £175 return, so more than the APD.
Have you looked for flights from NCL to CPH, ARN, OSL or MXP or maybe somewhere in Spain?