By Jon Robinson S&P Global has signed a deal for the most expensive office space in Manchester at Gary Neville’s landmark development in the city centre. The US giant has taken 19,695 sq ft of space at the £150m No.1 St Michael’s building which is currently under construction. The deal between the global financial firm and Relentless Developments breaks the record for the highest headline rent for offices in Manchester. The previous record was set by Pinsent Masons when it signed up to pay £43 per sq ft in July 2023. S&P Global will occupy the entire sixth floor of No.1 St Michael’s which will…