Originally Posted by
Tiger_lily
Can't help with the 4 seats though and you may have to look at other airlines other than SQ for this one to get the number of seats that you need.
Indeed - I suspect the planets will need to be in alignment, along with a lucky horse shoe, some clover and a rabbit foot to get 4 seats on SQ, especially on LHR-SIN.
4 seats isn't impossible on other carriers, LH and LX come to mind as having more seats at a time available.
Good luck to the OP in getting what they want though. It may take a fair bit of research via ANA / Expertflyer, as well as a bit of date flexibility, but hopefully it will all fall into place for them.