There seems to be a little chatter in the community about what Bigmouthmedia have done to incur the wrath of the Mighty Google as searching for their domain in Google isn't returning their homepage. This could be anything thing from a simple technical issue or a full blown homepage ban in Google.
Either way it isn't good for business, so lets look at a few things. First off the #1 placement is a 301 redirect which kind of reminds me of the old 301 Hijacking but IMO bigmouthmedia.com is too strong a web property to be hijacked in this way, unless the site was compromised? Maybe a hack but without any Google cache it's a tough one to see what G-maps.com had to take over the cache. But then you look deeper and G-maps.com and the co.uk are Big Mouth owned and are being 301’d in.
Only time will tell but it seems strange them not being at the top of Google for “search engine optimisation” as they have pretty much dominated that position.