I am not sure of the exact circumstances of your flight on Monday. However, the fog over the past few days has been, for much of the time, hovering right around our 'minimums'.
At a particular point on the descent (1000ft?), the tower will give the current RVR (Runway Visual Range) readings. If these are below the minimum, then the approach must be discontinued (go-around) at this point. You are not allowed to continue.
This is particularly frustrating in drifting fog because, sod's law, 60 seconds later (when you would have been at decision height), visibility may have increased to above our minima.
It is often a combination of good luck and good judgement which, in these marginal cases, allows a descent to continue when the aircraft immediately in front or behind you has had to go-around.
A challenging few days and a number of diversions.
In trim.
[ 12 December 2001: Message edited by: In trim ]
[ 12 December 2001: Message edited by: In trim ]