Hello Ian,
This medal and archive has surfaced a number of time over the last few years. The medal was sold by Noonans (then DNW) in 2004 in their December 2004 sale, hammer £3100 without the archive material which was sold separately in the March 2005 auction for £7500 (!). The medal and archive were reunited and, as you correctly state, sold by Spink in 2011 for £4800. The same lot was sold again by Noonans in 2013, hammer £5000, and again by Noonans in 2016 when I acquired the medal and archive for £4600. My interest in this material is entirely Boer War focussed but the early submarine story is also fascinating. Send me a PM with your email address and we can discuss this further. I did digitise the audio files which were on cassette tape and I now have as MP3 files and can share with you if you wish.
I was particularly interested in the records and photos of the Ladysmith Defenders annual dinner held from 1902 to 1951. Here is the signed menu from 1937 with many recognisable siege names.
and a photo of the, by then, depleted membership in 1951 Sharp is the bald chap seated cross legged on the floor with his hand in his lap
Regards
Paul