Are you sitting comfortably? Here's the bad news.
I've been doing a little research and no fewer than 16 of the top 40 marginal seats held by the Conservative party (and targeted by Labour) were represented by MPs (now candidates) who voted against plain packaging in March.
In contrast, only eleven of the top 40 Tory seats targeted by Labour are being fought by MPs/candidates who voted in favour of plain packaging.
In other words, a substantial number of MPs who are naturally opposed to excessive regulation could lose their seats. For the record they are:
Jackie Doyle-Price, Thurrock
Mark Spencer, Sherwood
Nigel Mills, Amber Valley
Paul Uppal, Wolverhampton South West
John Stevenson, Carlisle
David Morris, Morecambe & Lunesdale
Karl McCartney, Lincoln
Richard Fuller, Bedford
Simon Kirby, Brighton Kemptown
Mary MacLeod, Brentford & Isleworth
Nick de Bois, Enfield North
Ben Gummer, Ipswich
David Nuttall, Bury North
Chris Skidmore, Kingswood
Stephen Mosley, City of Chester
Esther McVey, Wirral West
As for the Tory candidates who supported plain packaging and are currently hanging on to their own marginal seats, they are:
Matthew Offord, Hendon
Peter Aldous, Waveney
Stuart Andrew, Pudsey
James Morris, Halesowen & Rowley Regis
Marcus Jones, Nuneaton
Richard Graham, Gloucester
Michael Ellis, Northampton North
Paul Maynard, Blackpool North & Cleveleys
Gavin Barwell, Croydon Central
Robin Walker, Worcester
Kris Hopkins, Keighley
I have focussed on Tory marginals targeted by Labour because they appear more vulnerable than Tory marginals targeted by the Lib Dems.
The elephant in the room is of course Ukip. Given that both Ukip MPs (Douglas Carswell and Mark Reckless) voted against plain packaging and the party is opposed to the smoking ban, the attraction of voting for the party - if you're libertarian on these issues - is obvious.
The problem is that a vote for Ukip in certain constituencies could result in the loss of some very good MPs who are naturally opposed to Big Government.
Personally, if my MP's voting record suggested a consistent commitment to small government and less regulation I would support them regardless of the party they represented.
If, on the other hand, their voting record indicated otherwise I would vote for someone else.
What I'm trying to say is, don't destroy the careers of politicians like David Nuttall or Karl McCartney just because you want to 'hurt' David Cameron.
Likewise, if your natural inclination is to vote for one of the mainstream parties, make an exception for the likes of Carswell and Reckless. I'm not a fan of defectors, mid parliament especially, but on the basis of their voting records they deserve our support.
See also the full list of MPs who voted against plain packaging in 2015 and the list of MPs who voted in favour of David Nuttall's ten-minute rule bill to amend the smoking ban in 2010.