Input-group trying to display GBP sign

[Waspman]

This is a strange one.

Have a program written in Bootstrap 4 / PHP / HTML

Only fonts used in program are Arial/Arial Unicode and font-waesome free.

Have used an input group to allow currency fields to have the currency symbol displayed before the entry. I used the code copied from the Bootstrap documentation.

                            <label class="col-md-3 control-label" for="payamount">Amount Paid:</label>
                            <div class="col-md-4">
                                <div class="input-group">
                                    <div class="input-group-prepend">
                                        <span class="input-group-text">£</span>
                                    </div>
                                    <input type="text"  class="form-control" id="payamount" name="payamount"  placeholder="0.00"  value=<?php echo $payamount ?>>
                                </div>
                            </div>

If I leave it with the dollar symbol as the prepend symbol it works exactly as expected, but if I change it to the UK pound sign (£) it just displays a “holder” symbol.

Elsewhere in the program in normal text the £ sign dispalys as expected.

Any ideas please?

Thanks.

[Waspman]

Although I am still trying to understand why the pound sign (£) doesn’t display if that character is entered from the keyboard, it does display if entered as £