In my opinion there will be hardly be any impact, especially if the shares are deposited at about the same time as the Half Yr announcement. Even if the share price changes, it is unlikely to be attributable to the bonus.
We have precedents in the case of TPS (1 for 5 bonus), Jubilee (1 for 10), NIC (1 for 10 bonus), NMG etc (1 for 10 bonus?).