File Mount Vernon Square residents got letters last week inviting them to a public meeting to meet the developers of the new Washington Convention Center, slated for groundbreaking this spring. Unfortunately, the letters arrived after the Oct. 21 meeting had already occurred. “It seems to me it’s always been very secretive,” 10th Street resident Elizabeth Cheely said. In spite of the late notice, the United House of Prayer still managed to pack the meeting with congregation members who vehemently opposed plunking the new convention center down in their neighborhood. (The church owns a 108-unit apartment building on 7th Street NW adjacent to the vacant two-block tract once reserved for a downtown campus of UDC.) Even without the formal invitation, 300 people turned out for last week’s meeting, but convention center community relations director Donna Potts claims not all the neighbors are opposed to the new center. “I have actually talked to a few people who were in favor of the convention center,” she says. “I don’t think those folks were as willing to stand up and talk.”