I can't find all the details right now but in 1970 there was some gathering of glass makers in London. I will try and see if I can find more details on who, but from what I've found so far there is no one with those initials.
I have found that an exhibition was held in December 1970 at the Park Square Gallery in Leeds owned by Mrs Sarah Gilchrist.
The archives are at
The University of Leeds
The Library.
http://www.leeds.ac.uk/library/spcoll/handlists/074MS712QueenSq.pdfThe info from that is as follows:
'26. Christmas exhibition, mainly of glass, sculpture and jewellery,
December 1970
Work by:- Brian Askwith, Terence Bennett, Richard Bonehill, Lynne Bradshaw,
Ingebord Bratman, Ralph Brown, Jane Bruce, Pamela and Christopher Burrows,
Stephen Chaplin, Ann Christopher, Jon Clark, Dillon Clarke, Martin Demaine,
8
Handlist 74
Wayne Filan, Alan Freer, Sam Herman, Susanna Heron, Fenella Hill, David
Hockney, Brian Illsley, Peter K Jackson, Duncan S James, Heskel Joory, Peter
Layton, Margaret Lovell, Mary Martin, Annette Meech, Breon O'Casey,
O'Donnell, Ric Oginz, Asiru Olatunde, Simon Pearce, Wendy Ramshaw, E
Russell, Pauline Solven, J Suhajek, Keith Tyssen, Austin Wright and Helga Zahn.
Also prints by: Patrick Caulfield, Elisabeth Frink, Terry Frost, John Hoyland and
Kenneth Martin.
1138-1206 Correspondence, 1970-1. 81 ff.
1207 Biographies of exhibitors, [1970]. 19 ff.
1208 Price list with annotations, [1970] 23 ff.
1209 Sales lists, [1970].11 ff.
1210 Rough accounts, [1970-1]. MS 10ff.
1211 Mounted press-cuttings, [1970]. 4 ff.
1212 Photocopies of press-cuttings, [1970]. 5 ff.
1213-1217 Miscellaneous publicity material about various exhibitors. 13 ff. '
There does not appear to be anyone in that list that would match the initials BW.
I wonder if it could have been an overseas glass maker come to London for that gathering, rather than a British maker?
I'm sure I read somewhere that Benny Motzfeldt for example also came over that year, but I cannot find my reference for that at the moment. And for example, Sam Herman, Wayne Filan, Jon Clark and Martin Demaine are all mentioned in that list along with Jiri Suhajek.
Sue if you are reading this

hello and for you -
In addition to this in December 1969 there was a Mdina Glass exhibition
information as follows:
'21. Glass exhibition, December 1969
Work from Mdina Glass, Malta.
950-959 Correspondence, 1969. 11 ff.
960-961 Mounted press-cuttings, 1969. 2 ff.
962-964 Miscellaneous financial documents, 1969. 3 ff. '