## Increase HORIZONTAL space inside legend
ggplot_padded <- function(x, w = 1){ # w=1 adds 1cm to horizontal space
    require(gtable)
    if (!gtable::is.gtable(x))
        x <- ggplotGrob(x)
    get_legend <- function(x){
        leg <- which(sapply(x$grobs, function(x) x$name) == "guide-box")
        x$grobs[[leg]]
    }
    g <- get_legend(x)
    # CASE-SPECIFIC: WITH 2 LEGEND ITEMS, POSITION TO BE ADJUSTED is 6
    # TWEAK THIS ON A CASE-BY-CASE... e.g. ADD LINES BELOW AS NEEDED
    # SIMILARLY FOR heights...
    g$grobs[[1]]$widths[6] <- g$grobs[[1]]$widths[6] + unit(w,"cm")
    x$grobs[x$layout$name == "guide-box"][[1]] <- g
    require(grid)
    grid.draw(x)
}
pdf("plot.pdf", width = 8, height = 5)
    ggplot_padded(p)
dev.off()