The new CIRRUS system at BA uses statistical data that is time of day and aircraft type specific to work out contingency fuel. Rather than just use 15 minutes as per SWORD, the new system knows when are the busy times (don't say always!). Hence arriving from Italy into LHR recently at 0930 we had 27 minutes cont fuel planned on CIRRUS. I have almost never seen it go below 15 minutes at LHR. However, arriving at Oslo at 10pm in good weather it is likely the cont fuel might be as low as 8 mins.
For once the system,at least on SH, seems to be working! And remember, one of our professional duties is to load more fuel if you think it is necessary. Let's not ever get into situation where the dispatchers make the decisions!