Bank Holiday Monday in Brighton

This story was written as a warm-up exercise at a training session in therapeutic storytelling. We had to choose a postcard and write a story with a main protagonist, a beginning, middle and end. so here it is:

Bank Holiday Monday - at last! I am desperate for a whole day of relaxation, switching off, chilling out. I've been working so hard - all the hours God sends at my desk at a leading City insurance company. At age 50 I need to keep proving my worth to the bosses. I dread the 'invitation' to take early retirement and be put out to grass.
My wife loves my salary. Always out shopping. Today we've come down to Brighton on the train. She has met up with some cronies of hers and gone off to shop the boutiques in the Lanes, high heels going clackety clack and shrill voices chattering nineteen to the dozen.  I, however, have ambled down to the seafront, breathing in the salty air, listening to the rhythm of the waves, the swoosh as the pebbles surge back and forth, the cry of the seagulls.
It's quite cool and damp. There was a rain shower an hour or so ago, but we were on the train then. I had watched the drops running down the windows as Trudy described her shopping plans in detail. All I wanted then, all I want now, is to sink into one of these deck chairs and descend into memories of my childhood, indulge in sentimental nostalgia. I ease myself into the chair, close my eyes and take myself back forty years to memories so vivid - all charged with a variety of emotions that wash over me, just as the sea washes the pebbles on the beach.
I become aware that someone has sat down in the deck chair next to me. How annoying! I hope desperately that they aren't the chatty, inquisitive, nosy sort of extravert who wants to meet a new friend. I just want some peace and quiet, to be left alone in my memories.
Then I hear a gentle humming. It's the tune of one of the songs of my youth. A song that recurs in my life, like an old friend that comforts me and gives me hope in the daily drudgery of existence. I start to hum along, not even wanting to look and see who is sitting next to me.
We change from humming to singing, sometimes stumbling over the words, filling in with la la la. In places we even manage two part harmony that thrills my heart. The sound of two voices intertwined never fails to delight me.
We stand up and sing even louder, competing with the noise of the sea. We are completely oblivious to passers-by who give us curious glances. Eventually we begin swaying, and then dancing, to the music. I feel so alive, connected to the the hugeness of life all around me.
Suddenly, it starts to rain again. I turn to my singing companion, but no-one is there, just an empty deck chair flapping in the wind. "Come back!" I call. "Who were you? How did you know my song? What made you come here today?" But no-one returned to me, no-one gave any answers or explanations.
On the train on the way home Trudy once again chattered about all her purchases and hoped that we would be home in time for Eastenders. I gazed once again at the raindrops on the window and secretly treasured the memory of the encounter with my unseen singing companion, glad to have another exquisite memory to sustain me through the daily grind.