Handling 404 Errors

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Jon Dunn: What would you do?
  
  A site relaunch means the mobile version of the site is redundant (m.domain.com) because the site has gone responsive.
  
  How do you handle the mobile pages that now 404? Do you 301 redirect them to the new responsive pages? Do you let them 404 and fall from the index? Or do you do something else?
  
  Many Thanks :)
• 
  Edwin Jonk: If for some reason an user follows a m-dot link on the interweb, the 404 would be quite disappointing. So I would 301.
• 
  Victor Castillejos: As +Edwin Jonk ;said 301 would be the best solution..