** Public transport operator rises as much as 5.2pct after Investec raises rating on stock to 'buy' from 'add'
** Investec says only about 1/3 of co's business directlyexposed to GDP changes
** Note adds that Regional bus business most exposed; GTRunit does not have revenue risk
** Go-Ahead outperforms FTSE 350 Travel & Leisure Index which is -0.6 pct; stock 7% below pre-Brexit level