Bolt Thrower are easily my favourite band right now. A midland band formed in the 80s, they're basically death metal but the vocals are arguably grind and they see themselves as a simply a (very) heavy metal band. They have an approach which is not super-technical but incredibly fussy with song structures and riff development. The fact their first (classic) album 'Realm of Chaos' was endorsed by Warhammer (and released on Earache) adds even more to their appeal. John Peel liked them a lot and they were instantly big in the UK but never crossed over like some of their contemporaries (Carcass, Deicide, Morbid Angel) in the early 90s. They had problems with the production on some records (which actually gave them more longevity as they aren't over-produced) and a few singer issues. But the original line-up is together now working on a new album and playing live sporadically.
They have kept going with a rare authenticity and have not put out a bad album. They're massive in Europe and in the last few years you can tell that their respect level is growing in the UK. This is because they're incredibly listenable and have some of the best riffs and heavy songs ever written. I loved Cenotaph (below) when I saw it on Headbangers Ball back in the day and I can't get enough of their entire back catalogue right now... if you like riffs you need this band in your life ASAP. They are without doubt one of best heavy metal bands to come from the UK.
Alone you stand - The final parody
Destined to silence - A memorial to mortality
Carved in stone - A tribute to the dead
For nameless victims - Whose litany is unread