Thank you for all your comments,when i took over the property the exterior finish on the entrance porch and stairs was flaky, i scraped all this away, which left the area pitted.
After cleaning, i applied( on the advice of a former builder at the local B&Q), self levelling compound, this was done in stages due to to access, the stairs were done last, prior to the application of Evo-stick super evo bond PVA ( which states to seal concrete floors;plaster;render;masonry; and is good for sealing) the finished floor was smooth but dusty, this was cleaned up and the PVA was applied, which cured the dust problem.
Smooth masonry paint from B&Q ( brick Red )dirt resistant;high quality acrylic formula ; specially formulated for use on brickwork ; stone ; concrete ; rendering & roughcast.
These tasks were done with regard to the weather which over the duration, was dry, overnight temps were 8 - 10 degrees, so i felt i had done everything right, it looked great, until the first rain some 4 days later, when part of the finish on the porch floor deteriorated, the stairs were unaffected ?????