Bet365 offer 7/4 about this, horses at the front of the market shortening all the time.
Another novelty market - SP of the Winner:
Under 16/1 6/4
16/1 - 33/1 6/4
over 33/1 2/1
Under 16/1 obviously contains the more fancied runners but you only need 6 to go off at 14/1 to make the bet value if my maths is correct? Last years under 16/1 bracket was:
11/2f
8/1 (Walsh ridden)
10/1
11/1
11/1
12/1 (McCoy ridden)
12/1
Dutching those would've given about a 4/9 shot. Granted the National market is not necessarily a balanced view point for this type of bet but if anything the obligatory shortening of all horses from the show onwards works in your favour with this bet.
The year before it was:
8/1jf
8/1jf
10/1 (McCoy)
12/1
14/1
14/1
So still a 10/11 shot dutched.
The market currently has 6 at worst prices and 1 at best prices at 14/1 or lower and whilst I expect the market will be 10 or 12/1 the field on Saturday morning I expect the number of horses under 16/1 to be at least 6 or 7 at the off, including the favourite, McCoy's selection, Pricewise main selection (?) and whatever the on the show gamble is....
As an aside it wouldn't have won on either the last 2 years, but you would've had a decent run for your money.
Looks more of a reflection of the huge overround for the ones at the head of the market that happens each year. To work out if it's worth a punt I think you'd need to group the unders for past 10 years say and work out how many times the unders actually won. Would give a better view in my opinion although working with obvious limited sample size.
Ok, results since 2014:
2004 6 qualifiers under 16/1, roughly 10/11 dutched, placings in the first four 2nd, LOST
2005 4, 5/4, 1st, WON
2006 6, 4/9, 1st 2nd 3rd, WON
2007 8, 2/5, 2nd, LOST
2008 7, 1/2, 1st 4th, WON
2009 7, 4/7, 2nd 3rd 4th, LOST
2010 7, 10/11, 1st 2nd 4th, WON
2011 8, 1/2, 1st 2nd 3rd, WON
2012 6, 10/11, 3rd, LOST
2013 7, 4/9, 2nd 3rd, LOST
So 10 races, 5 wins, 5 losses, only 1 dutch above evens(though Betfair SP would probably be a more accurate way to dutch them, effectively the lay dutch price), only once failed to have the runner up when not having the winner.
With Bet365 having the standout price at 7/4 I think placing e/w bets on higher priced horses and placing the returned half stake at 7/4 under 16/1 gives plenty of bullets for a profitable race.