Hi Again , took truck to mechanics on Thursday when the noise promptly disappeared only to come back again on Friday - So we pulled axle out on Saturday to investigate - bearing had lost some grease but not all - So elected to replace seal at this point as we don't have access to a press at home but .........
Whoops - got the wrong seal in my spares kit - so bearing re packed and repeat again with new seal in the week .
Apologies if this is getting tedious - more exciting posts later......and thanks for help .