When I was out in Lanzarote back in 2005, I dived with MA Diving in Puerto Del Carmen and found them to be a very professional outfit. Despite it being off-peak season, they still sorted out a good itinery of diving for me (sometimes just me!) including a couple of trips up to Mala (the German nudist colony) and some boat diving around the Puerto Del Carmen old harbour wrecks. I cannot recommend them highly enough!
M.A. Scuba Diving, Lanzarote, Canary Islands - Home
Despite their dutch origins, they had at least two English members of staff including Debs 'the Diving Diva' and Des - both of whom were very cool. I'd certainly be more than happy to dive with them again...