The listed company, which is now by far the UK's biggest employer of architects, looks set to snap up the London-based leisure and swimming pool specialist.
The deal would be yet another massive acquisition for the company, which has grown from almost nowhere to a dominant position in the market in just over three years.
The move is understood to be one of four takeovers SMC is planning for the near future, although it looks increasingly unlikely that all the deals will be completed before this Christmas, as was first predicted.
A source close to SMC told the AJ the S&P deal was a 'long way off' but said both sides were keen to 'see it through to a successful conclusion'.
S&P Architects came 77th in the 2006 AJ100, but that ranking belies its dominance in the swimming-pool sector, where it is the market leader.
The deal makes sense for SMC because its ambition is to have coverage in all the major architectural sectors, and to date it has not had much leverage in the leisure sector.
SMC has set up healthcare and education arms in an effort to take advantage of these burgeoning markets.
Among the high-profile schemes taken on by S&P is the 2012 Olympic Aquatic Centre, which it is designing in collaboration with Zaha Hadid.
Its other projects include a new 50m swimming pool in Cardiff and a leisure centre in Corby, Northamptonshire.
While S&P has been very successful domestically, the practice's senior management - which includes long-term managing director Robert Guy - is likely to be motivated by the financial clout a deal with SMC boss Stewart McColl would bring.
This could allow the practice to win more work overseas, a possibility that has motivated many of the firms that have so far succumbed to the temptations of SMC.
In the past calendar year, SMC has bought a host of practices, including Alsop Design and the Parr Partnership, the latter deal making it the biggest employer of architects in Scotland.