Why do people bet on grey horses?

Only three grey horses have won the Grand National since it began in 1839, with a total of four victories between them.

The Lamb won twice, in 1868 and 1871.

Exactly 90 years passed before the next grey winner, Nicolaus Silver, in 1961.

Another 61 years went by before the next and most recent winner, Neptune Collonges, in 2012.

This means a grey horse has won the Grand National on 2.3% of occasions - so what is their appeal to betters?

The primary reason for fewer grey victories is mathematical - they are a much rarer colour than other horses, with about one in 10 carrying the grey dominant gene.

Racing historian Michael Church has estimated the number of greys to have "hovered around 3%" of the total number of racehorses over the years.

Greys are actually usually born with a darker shade of coat, but progressively lose their colour over time as white hairs take over due to their genetic mutation.

Unlike white horses, their skin and eyes remain dark in colour.

Scientists have identified the genetic cause of a grey coat in horses, and have also found that 70-80% of grey horses that live beyond 15 years have melanomas and reduced lifespans as a result of the genetic mutation.

Out of a longlist of 78 racehorses in the 2026 Grand National, only seven grey horses were in contention - of which three made the shortlist of 55, and only one to the final field of 34.

Marble Sands is now the sole grey horse that has made it to the starting line-up.

Superstitions around grey horses and their success - or lack of - has been around for decades, with most theories not backed up by any hard evidence.

"Bet the grey on a rainy day" is an old phrase that leans into the unproven belief that grey horses perform better in muddy conditions.

The rarity of a grey horse on the Grand National start line has a 'lucky' appeal for superstitious betters, as well as the fact that they are simply easier to identify on the course among the more common darker shades.

Given the Grand National is likely to attract more casual punters as well as seasoned betters, it could be something as simple as wanting to be able to watch their horse that means bets are placed on greys.

However for some spectators, the relative lack of Grand National wins by greys has the opposite effect and is off-putting for placing wagers.

Coupled with historical rumours - not backed by science - that greys have a difficult temperament and are difficult to train, one thing that is certain about this shade of racehorse is that the superstitions surrounding them are not going away any time soon.

This article is the latest from BBC Sport's Ask Me Anything team.