I thought that I'd offer an identical service using my hardly-used @pwntter twitter account until such time as @big_ben_clock comes back on-line.
Code: There's two bash scripts, one to generate the BONGs and one to tweet them using TTYtter.
#bong n hours of the time (12 hour clock) mimicking @big_ben_clock
for (( i=1; i <= $I; i++ ))
echo -n "BONG "
#tweet bigben bongs while @big_ben_clock is down
/usr/bin/ttytter -keyf="/home/prawn/.ttytterkeypwntter" -ssl=1 -norc -hold=5 -status="$TWEET"
Simply use cron to fire off the bigben script on the hour.