Hello, my name is***** am a qualified lawyer and it is my pleasure to assist you with your question today.
Are they based in the UK?
By doing a search to see if they are mentioned anywhere else, I have found that there was a firm called Spencer Gibson & Son who were based at that address back in the 1980s. Looking at the Law Society now, there is no record of such a firm so the most likely scenario is that they have now ceased to operate and have closed down. For example if this was a small practice with just one or two partners, the death of these may have resulted in the closure of their practice - quite common with small firms like this one
I hope this has answered your query. I would be grateful if you could please take a second to leave a positive rating (3, 4 or 5 stars) as that is an important part of our process and recognises the time I have spent assisting you. If you need me to clarify anything before you go - please get back to me on here and I will assist further as best as I can. Thank you