Tom Cruise and Katie Holmes' marriage may be on the rocks, but perhaps the most important factor is the future of the couple's six-year-old daughter Suri.

It is rumoured Katie is seeking sole custody of the child, who was born in April 2006.

Dylan Howard, Editor in Chief of Celebuzz, says there are several reasons why that could be: "There could be a number of reasons for that, not the least being in a child custody battle like this, that if you do file for sole custody, ultimately you could end up making more money in terms of child support payments.

"But what actually went on behind the scenes to force Katie Holmes to file for divorce remains unseen at this point, and whether or not there was something more sinister, perhaps something more larger at play behind the scenes that we don't know about that forced her to file for sole custody remains to be seen."

The reasons behind the divorce and any potential custody battle are likely to remain private for the time being, though they will no doubt be a source of much speculation.