The absence of a service record, as Rosie says, almost certainly means it was lost to bombing in WW2, only about 4 in 1o survived so the odds are always against.
The absence of a medal card (these were not lost) again almost certainly means he served in UK and not overseas. (The alternative is that no medal card was prepared for him). Tens of thousands of men served in Labour Corps companies in agriculture, munitions supply and general labouring work. Just as likely to receive some sort of disability at home which warranted a later pension.
Did he have some special skill perhaps? Is there anything on his pension record that resemble a unit eg 534 AEC LC or similar?
MaxD