Nottingham Forest have re-signed Darius Henderson on a two-year contract.
The striker spent the second half of last season at the City Ground on a short-term deal, scoring twice in 11 Championship appearances.
And Forest manager Billy Davies saw enough to convince him Henderson is worth a longer-term investment.
Davies told the club website: "I am absolutely delighted to have Darius on board. He showed us what he is capable of in his spell with us last season and his vast experience will be invaluable to us going into the new campaign.
"To have landed such a key target at this stage in the summer is a huge bonus and it should give everyone great confidence for the future."
Henderson, who played in the Premier League with Watford in 2006/7, said: "I definitely want to get back into the Premier League and, having signed for Forest for another two years, that is my target.
"I believe we have a very strong chance of finishing in the top six next season and maybe, with a bit of luck, we could even claim a top two place.
"That would be great, but it will be difficult. There are some massive clubs with huge potential in this division but I am looking forward to the challenge.
"I feel as fit and fresh as I've ever done and now I will be able to settle and fully concentrate on the task ahead."
Larkins played for the Hammers' Under-21 side last season and was regularly watched by O's goalkeeper coach Kevin Dearden.
The 19-year-old has signed a one-year deal, and Dearden told the club's official website: "Jake is someone that I've watched personally on a number of occasions and have been impressed with him.
"I had a good conversation with Martyn Margetson (the goalkeeper coach at West Ham) and he came highly recommended, so we got him in to train with us towards the end of the season and he did very well.
"The gaffer, Kev (Nugent) and I liked what we saw and we believe he will be a valuable member of the squad and be able to push Jamie (Jones) for a starting place straight away."
