Penlee Park, near top entrance by Tennis Courts, other side of wall it the Well Fields pathway (leading to Alverton Well), other side of path is the Well Field Car Park ....
Is this not the gate post near the Abbey warehouse the slip that you walk along to get to the Abbey warehouse and this post is on your right? (only a guess)
Of course you have deary ... it was on Picture Penzance, ... you know that community site that some chap wassecall, Halfhidden or something and some flower by the name of Sparky set up a year ago ... you know ...